DOCSLIB.ORG

Physics First Secondary 2020

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physics First Secondary 2020 Physics first Secondary 2020 1st Session Gravitational Field The gravitational field: ● The universal gravitational law states that the gravitational attraction between two bodies is inversely proportional to square the distance between their centers. Thus, the gravitational force decreases gradually as the distance increases till the distance between the centers of the two bodies reaches a point at which the attraction ceases. ● Within this distance, there is a region in which the gravitational force appear, this region is called the gravitational field. Deduction of the gravitational field intensity (g): ● By assuming that a body of mass 1kg is placed in the Earth’s gravitational field and at a distance r from the center of the Earth, then the attraction force of the Earth to the body: F = mg = g……………1 And by applying the universal gravitational law: F = G = …………2 From 1 and 2: g = Where : (M) is the mass of the Earth that equals (5.98×1024kg). If the body is at: The Earth’s surface. A height (h) above A depth (h) below the the Earth’s surface. Earth’s surface. Then g = g = g = Where: (R) is the radius of the Earth that equals 1 MSE Physics first Secondary 2020 ● From the previous we notice that the gravitational field intensity at a certain point equals numerically the acceleration due to gravity of the Earth at this point. The gravitational field intensity: It is the gravitational force acting on a mass of 1 kg at a certain point. To compare the acceleration due gravity for two planets: = Note: The Earth is not perfectly spherical but it is oblate spheroid (a sphere that is squashed at its poles and swollen at the equator) and that is due to the centripetal force that originates from the rotation of the Earth around itself. The factors that affect gravitational field intensity (g) at a point: Mass of planet: Distance from the center of the The gravitational field intensity is planet: directly proportional to the mass The gravitational field intensity of the planet when the distance is inversely proportional to between the point and the center square the distance from the of the planet is center of the planet. constant. ∆g Slope = 1 = GM ∆g ∆ Slope = = r ∆ g = 퐆퐌 퐫ퟐ Example 1: A planet has a mass twice that of Earth and a diameter twice that of Earth. Find the ratio of the acceleration due gravity of the two planets. 2 MSE Physics first Secondary 2020 Answer: g Mp = 2 Me R1 = 2 Re = ? g g = = = g Example2: A satellite of mass 104kg orbits the Earth at a height of 600km from its surface, calculate: a) The acceleration due to the gravity of the Earth that affects the satellite on its orbit. b) The weight of the satellite in its orbit (Knowing that: R = 6378km, M = 5.98×1024kg, G = 6.67×10-11n.m2/kg2) Answer: m = 104kg h = 600km R = 6378km M = 5.98×1024kg G = 6.67×10-11N.m2/kg2 g = ? w = ? 11 a) g = = = = 8.19 m/s2 b) w = mg = 8.19 × 104N HW 1. The acceleration due to Earth’s gravity is…………… a) a general universal constant b) changeable according the height from the Earth’s surface c) different through the seasons of the year d) changeable depending on the distance between Earth and Sun 3 MSE Physics first Secondary 2020 2. A planet of mass 5.98×1024kg and its radius = 6378km, if G = 6.67×10-11 N.m2/kg2, so the intensity of the planet’s gravitational field at a point that lies at a distance 36000km from its surface equals…………..N/kg. a) 22.2×104 b) 22.2×102 c) 22.2×10-2 d) 22.2×10-4 3. On the scale of a building, gravitational field is……….. a) increasing b) decreasing c) uniform d) varying 4. Which of the following affect the strength of the gravitational field on the surface of a planet?........... (more than one answer is correct) a) The mass of the object at the surface b) The mass of the planet c) The radius of the planet d) The presence of air at the surface of the planet 5. Assign the acceleration of the Moon the symbol am and the mass of the Moon Mm. If a satellite with a mass Ms was placed in the same orbit of the Moon at the same speed, what is the gravitational field strength at the satellite’s orbit?............... a) am b) (Ms/Mm) am c) (Mm/Ms) am d) (Ms+Mm) am/Ms 6. If the acceleration due to gravity of the Earth at the orbit of a satellite that orbits the Earth is 2.5 m/s2, then the distance between the satellite and the Earth’s surface (h) equals…………. (Where: R is the radius of the Earth and the acceleration due to gravity at the Earth’s surface = 10 m/s2) a) 2 R b) R c) d) 7. If R is the radius of the Earth, so the height at which the weight of a body becomes its weight on the surface of the Earth is…………… a) 2 R b) R c) d) 4 MSE Physics first Secondary 2020 8. At a place, value of (g) is less by 1% than its value on the surface of the Earth (radius of Earth (R) = 6400 km). The place is………… a) 64km below the surface of the Earth b) 64km above the surface of the Earth c) 30km below the surface of the Earth d) 32km above the surface of the Earth 9. An object has a mass of 50kg and a weight of 500N when it is resting on the surface of the Earth. If it is moved to a height equal to three times the Earth’s radius, what is the object’s new weight?..................... a) 300 N b) 31.25 N c) 130 N d) 60.5 N 10. Two asteroids in the space are close enough to each other. Each has a mass of 6.69×1015 kg. If they are 100000 m apart, what is the gravitational acceleration that they experience?................... a) 3.89×1010 m/s2 b) 5.12×104 m/s2 c) 2.99×1011 m/s2 d) 4.46×10-5 m/s2 11. Two asteroids, one with a mass of 7.12×1018 kg and the other with a mass of 5.33×108 kg and the distance between them is 10×1010 m. What is the acceleration of the smaller asteroid?................. a) 3.79×105m/s2 b) 9.41×10-7m/s2 c) 4.75×10-14m/s2 d) 6.11×10-24m/s2 12. When climbing from the sea level the top of mount Everest, a hiker change elevation by 8848 m. By what percentage will the gravitational field of the Earth change during the climb?................ (where: the Earth’s mass is 6×1024 kg and its radius is 6.4×106 m) a) It will increase by approximately 0.3 % b) It will decrease by approximately 0.3 % c) It will increase by approximately 12 % d) it will decrease by approximately 12 % 5 MSE Physics first Secondary 2020 2nd Session Satellites ● Man has dreamed for centuries to explore the space and to achieve that dream, he continued developing probes and rockets that launch space ships to orbit the Earth or reach further to another planet like Mars. That dream has come true on the 4th of October 1957 when the first satellite (Sputnik) has sent into space. ● That was followed by sending other satellites and stepping onto the Moon. Still space exploration continues successfully. The idea of launching a satellite: ● A satellite in its orbit is considered as an object that falls freely towards the Earth’s surface (because it is under the effect of Earth’s gravity). In spite of this it never reaches the Earth’s surface. Isaac Newton explained this where he imagines that when projecting a cannon projectile from the top of a mountain in a horizontal direction (neglecting the air resistance): ● The projectile moves through a certain horizontal distance before falling on the ground. By increasing the velocity of projection, the horizontal distance moved by the projectile before falling on the ground increases. ● At a certain projecting velocity, where the curvature of the projectile path equalize with the curvature of the Earth’s surface, the projectile orbits the Earth in a roughly circular path and it becomes a follower of the Earth and named a satellite and this velocity is called the orbital velocity of the satellite. The orbital velocity of a satellite: It is the velocity that makes the satellite orbit the Earth in a roughly circular path where it is still at a constant distance from the Earth’s surface. Deducing the orbital velocity of a satellite (v) ● Assume that a satellite of mass (m) moves with a velocity (v) in an orbit of radius (r) around the Earth of mass (M) as in figure: 6 MSE Physics first Secondary 2020 − The force of attraction between the Earth and the satellite is given by the relation: F = G − The force of attraction between the Earth and the satellite is normal to the direction of the motion of the satellite so it makes the satellite move in a circular path: F = So the attraction force between the Earth and the satellite is the same centripetal force that acts on the satellite. ∴ G = , v2 = ∴ v = √ Where (G) is the gravitational constant and if the height that the satellite was launched to is (h) and the radius of the Earth is (R): r = R + h ∴ v = √ The factors that affect orbital velocity of a satellite: The planet mass: The orbit radius: Orbital velocity of a satellite is Orbit velocity of directly proportional to the square a satellite is root of the mass of the planet at inversely constant radius of proportional to the the orbit.
Load more

Recommended publications
  • Up, Up, and Away by James J
    www.astrosociety.org/uitc No. 34 - Spring 1996 © 1996, Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, CA 94112. Up, Up, and Away by James J. Secosky, Bloomfield Central School and George Musser, Astronomical Society of the Pacific Want to take a tour of space? Then just flip around the channels on cable TV. Weather Channel forecasts, CNN newscasts, ESPN sportscasts: They all depend on satellites in Earth orbit. Or call your friends on Mauritius, Madagascar, or Maui: A satellite will relay your voice. Worried about the ozone hole over Antarctica or mass graves in Bosnia? Orbital outposts are keeping watch. The challenge these days is finding something that doesn't involve satellites in one way or other. And satellites are just one perk of the Space Age. Farther afield, robotic space probes have examined all the planets except Pluto, leading to a revolution in the Earth sciences -- from studies of plate tectonics to models of global warming -- now that scientists can compare our world to its planetary siblings. Over 300 people from 26 countries have gone into space, including the 24 astronauts who went on or near the Moon. Who knows how many will go in the next hundred years? In short, space travel has become a part of our lives. But what goes on behind the scenes? It turns out that satellites and spaceships depend on some of the most basic concepts of physics. So space travel isn't just fun to think about; it is a firm grounding in many of the principles that govern our world and our universe.
    [Show full text]
  • Surface Gravity and Interstellar Settlement (Version 3.0 September 2016)
    Surface Gravity and Interstellar Settlement (version 3.0 September 2016) by Gerald D. Nordley 1238 Prescott Avenue Sunnyvale, CA 94089-2334 [email protected] Abstract. Gravity determines the scale of many physical Jupiter's inner satellites melts the ice of Europa and drives phenomena on and above a world's surface. Assuming that tool- volcanoes on Io, and that Mars in the past has had rain and using intelligences come from, and would settle, worlds with solid floods serves notice that worlds that are significantly less surfaces and gravities equal or less than that of their origin, we massive than Earth and have significantly less surface gravity note that such worlds in the Solar System have surface gravities can still have the deep atmospheres and liquid water significantly lower than that of Earth. The distribution of these temperatures needed to sustain life. surface gravities clumps around factors of about 2.5 and favors worlds with about one-sixth Earth gravity, conventionally 2. Surface Gravity Basics considered too small to retain atmospheres. Titan, however, Mass is, roughly, a measure of the amount of substance. shows that low surface gravity does not, in itself, preclude the Weight is the force by which that substance is attracted to presence a substantial atmosphere. Where small worlds have another mass. This force is directly proportional to the product of low exobase temperatures,and protection from stellar winds, both masses and inversely proportional to the square of the substantial atmospheres may be retained. distance between them. A spherically symmetric planet can be Significantly lower surface gravity affects a number of physical treated as if all the mass were at the center, so the relevant phenomena that affect environment and technological evolution-- distance is the radius from the center to the object.
    [Show full text]
  • Effect of Gravity on Current & Their Implications on Planets
    Crimson Publishers Research Article Wings to the Research Effect of Gravity on Current & Their Implications on Planets Saifullah Khalid* IEEE, India Abstract ISSN: 2640-9739 any variations in the effect of gravity at the atomic level and macroscopic level. The effect of gravity has beenThis paper calculated presents for various the effect planets. of gravity Consequently, on the atomic suggestions level. Various have researchbeen made has for been the considered space equipment to find manufacturers to consider the variation in current density due to gravity for the planets. Keywords: Gravity; Current; Charge; Earth; Planets Introduction Anything that has mass has gravity too. Objects with greater mass have greater gravity. With distance also, gravity gets weaker. Therefore, the smaller the bodies are, the greater their gravitational force is [1-5]. The gravity of Earth originates from all of its mass. All its mass makes the whole mass in the body a combined gravitational pull on. If we are on a planet *1Corresponding author: Saifullah Khalid, Member, IEEE, India with less mass than Earth, we’d be weighing less than here. Gravity is a fundamental force of Nature, one we Earthlings prefer to take for granted. And you can’t blame us. Having evolved Submission: March 24, 2021 in Earth’s climate throughout billions of years, we are used to living with the tug of a steady Published: August 03, 2021 1g (or 9.8m/s2). Yet gravity is a very tenuous and precious thing for those who have gone into space or set foot on the Moon [6]. Isaac Newton and Albert Einstein’s works dominate the Volume 2 - Issue 2 development of the theory of gravity.
    [Show full text]
  • PHYSICAL GEOLOGY (WITH LABORATORY) Syllabus EPS 3300 – PHYSICAL GEOLOGY (4 Crs
    Kingsborough Community College The City University of New York Department of Physical Sciences EPS 3300 – PHYSICAL GEOLOGY (WITH LABORATORY) Syllabus EPS 3300 – PHYSICAL GEOLOGY (4 crs. 6 hrs.) Study of the nature of the Earth and its processes includes: mineral and rock classification, analysis of the agents of weathering and erosion, dynamics of the Earth’s crust as manifest in mountain building, volcanoes and earthquakes, recent data concerning the geology of other planets, field and laboratory techniques of the geologist. ----Prerequisites: Passed, exempt, or completed developmental course work for the CUNY Assessment Tests in Reading, Writing, and ACCUPLACER CUNY Assessment Test in Math or Department permission ----Required Core: Life and Physical Sciences----- Flexible Core: Scientific World (Group E) Section: SECTION NUMBER Time: LECTURE AND LABORATORY SCHEDULE FOR SECTION Room: ROOM (S) FOR SECTION Instructor: INSTRUCTOR FOR SECTION Email: EMAIL ADDRESS FOR INSTRUCTOR FOR SECTION Office Hours: OFFICE HOURS FOR INSTRUCTOR FOR SECTION Source materials: An Introduction to Physical Geology10th or 11th or latest edition, by Tarbuck, Lutgens & Tasa Student Learning Outcomes Students will: Differentiate between the three types of plate boundaries by noting common geologic features and processes. Classify common physical properties and differentiate minerals and rocks. Summarize the relationship between the chemical and physical properties of minerals. Analyze igneous, metamorphic, and sedimentary rocks to determine how they formed. Compare how different types of magma form and explain their relationship to the formation of intrusive and volcanic igneous features. Compare and contrast weathering among different rock types and different environments. Identify strata, faults, and folds in geologic sections and summarize the forces and tectonic settings that lead to their formation.
    [Show full text]
  • Summary of Lesson
    Energy Skate Park Name High School Student Activity Class Open the TI-Nspire document energy-skate-park.tns. In this simulation, you will observe the changing potential and kinetic energies of a skateboarder-celestial body system as she moves over a track with negligible friction. You will also explore the relationship between the system’s potential and kinetic energy, and how they affect the total energy of the system. Finally, you will explore the impact of friction on these potential and kinetic energies. Read the information on page 1.1. Move to page 1.2. To start the simulation, select and drag the skateboarder up to the top left side of the track. Then, release him. You will see the skateboarder moving up and down along the skateboarding track on Earth. The skater’s motion follows a predictable path: 1. The skater starts from a stationary position. 2. The skater’s direction of motion changes. 3. The downward motion of the skater momentarily becomes horizontal at the bottom of the skating ramp, and then changes direction in an upward direction. 4. The skater nears the top of the skating ramp on the other side, momentarily stops, then changes direction and starts moving again. 5. The downward motion of the skater momentarily becomes horizontal at the bottom of the skating ramp, and then changes direction in an upward direction. 6. The skater reaches the top of the skating ramp where he originally started, momentarily stops, then it resumes a new cycle of movement. Part 1: Exploring Potential Energy 1. Wait until the skateboarder reaches the top part of the ramp and select the Pause button .
    [Show full text]
  • 8. Newton's Law Gravitation.Nb
    2 8. Newton's Law Gravitation.nb 8. Newton's Law of Gravitation Introduction and Summary There is one other major law due to Newton that will be used in this course and this is his famous Law of Universal Gravitation. It deals with the force between any two massive objects. We will use the Law of Universal Gravitation together with Newton's Laws of Motion to discuss a variety of problems involving the motion of large objects like the Earth moving in orbit about the Sun as well as small objects like the famous apple falling from a tree. Also it will be shown that Newton's 3rd Law of Motion follows as a consequence of Newton's Law of Universal Gravitation. Some additional topics that related to Newton's 1st and 2nd Laws of Motion also will be discussed. In particular, the concept of the Non-Inertia Reference Frame will be introduced and why it is useful. Also it will be shown how Newton's 1st Law and 2nd Law are NOT valid in Non- Inertial Reference Frames. It will be shown what is necessary to "fix-up" Newton's 2nd Law so it works in Non-Inertial Reference Frames. In particular, the examples of accelerated cars and elevators are used to illustrate the concept of the Non-Inertial Frame. The Four Fundamental Forces of Nature: There are four basic or fundamental forces known in nature. These forces are gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. The force of gravity is described by Newton's Law of gravitation and the more recent modification called General Relativity due to Einstein.
    [Show full text]
  • Reduced Gravity: Effects on the Human Body an Educator Guide
    Reduced Gravity: Effects on the Human Body An Educator Guide Reduced Gravity: Effects on the Human Body A Digital Learning Network Experience Designed To Share NASA's Space Exploration Program This publication is in the public domain and is not protected by copyright. Permission is not required for duplication. Reduced Gravity: Effects on the Human Body Page 2 of 38 DLN-08-01-2008- JSC Table of Contents Digital Learning Network Expedition....................................................... 4 Expedition Overview ................................................................................. 5 Grade Level Focus Question Instructional Objectives National Standards.................................................................................... 5 Pre-Conference Requirements.................................................................6 Online Pre-Assessment Pre-Conference Requirement Questions Answers to Questions Expedition Videoconference Guidelines.................................................10 Audience Guidelines Teacher Event Checklist Expedition Videoconference Outline.......................................................12 Pre-Classroom Activities..........................................................................11 The Water Mystery Bag of Bones Post Conference........................................................................................19 Online Post Assessment Post-conference Assessment Questions NASA Education Evaluation Information System ..................................20 Certificate of Completion..........................................................................21
    [Show full text]
  • Geological Survey
    BULLETIN UNITED STATES GEOLOGICAL SURVEY 2STo. 48 WASHINGTON GOVERNMENT PRINTING OFFICE 1SSS UNITED STATES GEOLOGICAL SURVEY J. W. POWELL, DIRECTOR ON THE FORM AND POSITION OH' THE SEA LEVEL WITH SPECIAL UEKEIIENCE TO ITS DEPENDENCE OX SUPEKiriCIAL MASSES SYMMETRICALLY DISPOSED ABOUT A NOKMAL TO THE EAKTH'S SUKFACE ROBERT SIMPSON WOODWARD WASHINGTON . - GOVERNMENT PRINTING OFFICE 1888 CONTENTS. Page. Key to mathematical symbols ............................................... 9 Letter of transmittal........................................................ 13 I. Introduction..... .................................................... 15 1. Form and dimensions of sea-level surface of earth. Close approxi­ mation of oblate spheroid. Eolation of actual sea surface or geoid to spheroidal surface. A knowledge required of form of geoid by geodesy, of variations in form and position by geology. Difficulties in way of improved theory ......................... 15 2. Class of problems discussed in this paper........................... 16 3. R6sum6 of results attained......................................... 17 A. THEORY. II. Mathematical statement of problem ............ ...................... 18 4. Fundamental principle and equation............................... 18 5. Dimensions of earth's ellipsoid and sphere of equal volume.......... 19 6. Derivation of equation of disturbed surface ........................ 19 III. Evaluation of potential of disturbing mass of uniform thickness....... 21 7. Determination of potential iu terms of rectangular and
    [Show full text]
  • Space Mathematics, a Resource for Teachers Outlining Supplementary
    DOCUMENT RESUME ED 061 104 SE 013 589 AUTHOR Reynolds, Thomas D.; And Others TITLE Space Mathematics, A Resource for TeachersOutlining Supplementary Space-Related Problems in Mathematics. INS ITUTION National Aeronautics and SpaceAdministration, Washington, D.C. REPORT NO NASA-EP-92 PuB DATE Jan 72 NOTE 130p. AVAILABLE FROMSuperintendent of Documents, Government Printing Office, Washington, D.C., 20402 ($2.00,Stock Number 3300-0389) EDRS PRICE MF-$0.65 BC-$6.58 DESCRIPTORS *Aerospace Education; *Instruction; Instructional Materials; *Mathematical Applications;Mathematical Enrichment; Mathematics Education;*Resource Materials; *Secondary School Mathe atics ABSTRACT This compilation of 138 problems illustrating applications of high school mathematicsto various aspects of space science is intended as a resource fromwhich the teacher may select questions to supplement his regularcourse. None of the problems require a knowledge of calculusor physics, and solutions are presented along with the problem statement.The problems, which cover a very wide range of difficulty, are grouped intochapters as follows: Conversion Factors, Notation,and Units of Measurement; Elementary Algebra; Ratio, Proportion, andVariation; Quadratic Equations; Probability; Exponential andLogarithmic Functions; Geometry and Related Concepts; Trigonometry;Geometry and Trigonometry Related to the Sphere; and ConicSections. A bibliography is provided. (MM) U.S. DEPARTMENT OF HEALTH. EDOCATION & WELFARE OFFICE OF EDUCATION THIS DOCUMENT HAS BEEN REPRO- DUCED EXACTLY AS RECEIVED FROM THE PERSON OR ORGANIZATION ORIG- INATING IT POINTS OF VIEW OR OPIN IONS STATED DO NOT NECESSARILY REPRESENT OFFICIAL OFFICE OF EDU- CATION POSITION OR POLICY A REM MOE iFflR _DOERS outlining supplementary space- rated PRAMS in mathematics 4 41 Cf") national aeronautics and space administration cY) A RESOURCE MR TEACHERS outlining supplementary space- related problems in mathematics Developed at Duke University under the auspices of the Department of Mathematics NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Washington, D.C.
    [Show full text]
  • Up Vs Down Part 2
    TEACHER RESOURCE STARDOME OBSERVATORY & PLANETARIUM FACTS, RESOURCES AND ACTIVITIES ON... PARTDOWN GravityUP is what gives us a sense VS.of what is up and down. ( 2) No matter where you stand on Earth – gravity will tell you that down is towards the centre of the Earth and up is towards the sky. The idea that up is north and down is south is entirely a matter of perspective. The first cartographers were from the northern hemisphere, so it is with their perspective that many of todays maps are made. Gravity is the attractive force between two objects, with the larger object exerting a stronger gravitational pull on the smaller object. This is why the Sun (99.9% of the mass of our Solar System) pulls all the planets into an orbit around itself, and why the Earth pulls the Moon (0.01% of Earth’s mass) into an orbit around itself. Gravity also explains why the Moon pulls objects (like astronauts) to its surface with less force than when objects are on the Earth’s surface. Check out the link below to watch astronauts ‘bounce’ on the Moon; it’s just the weaker gravitational force that causes this. The direction of ‘down’ on the Moon is towards the centre of the Moon, just like ‘down’ on Earth is towards the centre of the Earth. But what about up and down on smaller objects, like a space station? Astronauts living on a space station appear to float through the air. They have no concept of which way is up or down because the space station doesn’t have enough gravitational pull to give them that orientation.
    [Show full text]
  • SCIENCE - GRADE 5 Monday, May 18 – Friday, May 22
    SCIENCE - GRADE 5 Monday, May 18 – Friday, May 22 PURPOSE Grade Level Expectation: 5-PS2-1 (New Material) I can support an argument that the gravitational force exerted by Earth on objects is directed down. WATCH Monday: In Your World: Analyze this photo gallery. What do you notice about the birds? How are they remaining in the air? Is gravity different on birds than other animals and objects? Tuesday: Watch this video, Good Thinking!—Falling 101, to learn more about gravity and how matter, mass, and air resistance impact the gravitational force on objects. For a screen free option, read the Gravity Fact Sheet. Wednesday: Watch this video, Gravity & Inertia to learn more about the center of gravity, inertia, and how more or less mass affects the gravitational force on objects. For a screen free option, read the Gravity Fact Sheet. Thursday: Watch this video, Gravity 2: Air Resistance, to learn more about air resistance on objects of varying weights. PRACTICE The following activities provide opportunities for students to practice their learning. Monday: Watch this video to learn more about the Center of Gravity. For practice, try finding the center of gravity with three objects at home. Do this by balancing it on your finger or another object. When an object is balanced, you have found the center of gravity. Using your observations how might this relate to a bird’s flight? Tuesday- Complete Galileo’s Balloon Investigation. Using your observations from the investigation, support the provided claim with evidence and reasoning. You may refer to the Gravity Fact Sheet and Tuesday discussion questions for additional support.
    [Show full text]
  • Gravity Is a Force Exerted by Masses
    KEY CONCEPT Gravity is a force exerted by masses. BEFORE, you learned NOW, you will learn • Every action force has an equal • How mass and distance and opposite reaction force affect gravity • Newton’s laws are used to • What keeps objects in orbit describe the motions of objects • Mass is the amount of matter an object contains VOCABULARY EXPLORE Downward Acceleration gravity p. 381 How do the accelerations of two falling weight p. 383 objects compare? orbit p. 384 PROCEDURE MATERIALS • golf ball 1 Make a prediction: Which ball will • Ping-Pong ball fall faster? 2 Drop both balls from the same height at the same time. 3 Observe the balls as they hit the ground. WHAT DO YOU THINK? •Were the results what you had expected? • How did the times it took the two balls to hit the ground compare? Masses attract each other. When you drop any object—such as a pen, a book, or a football—it falls to the ground. As the object falls, it moves faster and faster. The fact that the object accelerates means there must be a force acting on VOCABULARY it. The downward pull on the object is due to gravity.Gravity is the Create a four square force that objects exert on each other because of their masses. You are diagram for gravity in your notebook. familiar with the force of gravity between Earth and objects on Earth. Gravity is present not only between objects and Earth, however. Gravity is considered a universal force because it acts between any two masses anywhere in the universe.
    [Show full text]