Review for ICA: Newton S 2Nd and 3Rd Law, Inertial and Non-Inertial Frame of Reference

Review for ICA: Newton’s 2 nd and 3 rd Law, Inertial and Non-inertial Frame of Reference

Inertial vs Non-inertial

1. Decide if each situation is an inertial or non-inertial frame of reference. a) I am sitting on a train moving at a uniform 60 km/h. b) The driver sees a tree blocking the rails. The driver slams on the brakes. c) The train starts to move after the tree is removed. d) The driver decides to continue but at a slower constant speed of 50 km/h.

Newton’s 3rd Law

2. A person exerts an upward force of 40. N to hold onto a bag of groceries. Describe the “reaction” force by stating a) its magnitude b) its direction c) on what object is the force exerted d) by what object is the force exerted

3. Each team in a tug-of-war pulls with equal force on the other team. Since the forces are equal and opposite, what determine which team will win?

4. Name 2 pairs of action-reaction forces in the diagram below.

5. What is the action-reaction pair for this situation: Mrs. Bain hammering a nail into the wall.

6. If an object has no acceleration, does this mean no forces are acting on it? Explain.

Newton’s 2nd Law (Draw FBDs!)

7. A man pushes a 58.5 kg sofa 2.30m across a carpet with a horizontal force of 345 N. If the coefficient of friction is 0.55, how long does it take the man to move the sofa? (Assuming it started from rest)

8. A man pushes a crate along the floor with a coefficient of friction of 0.48 until it reaches a speed of 6.25 m/s at which time the man stops pushing. How far across the floor will the crate slide after the man stops pushing?

9. A 640 kg elevator is supported by a cable. Find the tension in the cable if the elevator is … a) moving up at a constant speed of 3.00 m/s b) moving down at a constant speed of 3.00 m/s c) accelerating up at a constant speed of 3.00 m/s2 d) accelerating down at a constant speed of 3.00 m/s2 10. A 0.100 g spider is descending a web strand by applying a force of 5.65 x 10-4 N. What is the acceleration of the spider? Ignore air resistance.

11. What of these causes a change in friction: a) surface area b) mass c) weight d) speed e) velocity f) surface type

, Questions 9, 10 Page 171, Question 13

Answers: 1. a) Inertial b) non-inertial c) non-inertial d) inertial 2. a) 40. N b) downward c) person d) grocery bag 3. Mass of each team (larger mass wins) 4. Person 1 pushes Person 2, Person 2 pushes Person 1 Person 1 pushes down on ground, ground pushes up on Person 1 Person 2 pushes down on ground, ground pushes up on Person 2 5. Nail hits wall, wall hits nail 6. No- you may have equal forces that cancel out 7. 3.01s 8. Answer 4.15m 9. a) 6270 N [up] b) 6270 N [up] c) 8190 N [up] d) 4350 N [up] 10. -4.15 m/s2 11. weight, mass, surface type (b, c, f)