ACCELERATION AND MOMENTUM WHAT IS THE SECOND LAW OF MOTION? • Newton’s Second Law of Motion- the acceleration of an object is related to the object’s mass and to the amount of force applied to the object. • 푓표푟푐푒 = 푚푎푠푠 × 푎푐푐푒푙푒푟푎푡푖표푛 • A large force on an object with a small mass results in a large acceleration. • A small force applied to an object with a large mass causes small acceleration. • When a force is applied, objects with less mass accelerate more quickly. • 2 results of Newton’s Second Law: • For a given net force, objects with a greater mass have less acceleration. • For objects of a given mass, a greater force results in a greater acceleration. WHAT IS NEWTON’S THIRD LAW OF MOTION? • Newton’s Third of Motion- For every action, there is an equal and opposite reaction. • Anytime one object exerts a force on another object, a pair of forces acts. • An action-reaction pair of forces. • The two forces have the same strength but act in opposite directions. • If the objects have different masses, the object with less mass will move more but still exert the same force. WHAT IS MOMENTUM? • Momentum- the quantity that measures both the mass of the object and how fast the object is moving. • 풎풐풎풆풏풕풖풎 = 풎풂풔풔 × 풗풆풍풐풄풊풕풚 • An object is easier to stop when it is moving slowly compared with when it is moving rapidly. • The greater the object’s momentum, the more force and time it takes to bring it to a stop. • A baseball has more momentum than a tennis ball when the 2 are traveling at the same speed because the baseball has more mass. • A tennis ball can have more momentum than a baseball if the speed of the tennis ball is great enough. HOW IS MOMENTUM CONVERTED?

• Conservation of momentum- the total momentum does not change if there is no outside forces acting on the system. • Look at the picture. Before the girl pushed the boy, the total momentum of the skaters was zero. The total momentum cannot change. • The girl must have enough momentum to the left to cancel the boy’s momentum to the right. HOW DO WEIGHT AND MASS COMPARE?

• The weight of an object depends on its location in the universe and how much gravity is pulling on it. • The mass of an object does not change. WHAT IS WEIGHTLESSNESS?

• When something is freefalling, a scale would not be able to read its weight, so the object is weightless. • When an astronaut is in space, they are freefalling.. • Since everything in the spacecraft is falling together, the weight of any object cannot be detected. • To simulate weightlessness, you can work underwater because water reduces your weight when your submerged. • Gravity and inertia keep a satellite in orbit. • Both motions happen continuously, and they combine to keep a satellite in a curved path. • Placing a satellite in orbit requires accelerating it to a sideways velocity great enough to keep its path of motion from colliding with the surface of the Earth.