Physics Chapter 4 Review Name:______
Approximate g as 10 m/s2. Use GUESS method on problems. Date:______Period:______
1. Newton’s First Law states that an object _____.
a. at rest will remain at rest unless acted on by an outside force
b. will continue moving at the same velocity unless acted on by an outside force
c. will continue moving in a straight line unless acted on by an outside force
d. that is not moving will never move unless a force acts on it
e. all of the above
2. The law of inertia applies to _____.
a. moving objects b. objects at rest c. both moving and nonmoving objects
3. After a cannon ball is fired into frictionless space, the amount of forced needed to keep it going equals _____.
a. twice the force with which it was fired
b. the same amount of force with which it was fired
c. on half the force with which it was fired
d. one quarter the force with which it was fired
e. zero, since no force is necessary to keep it moving
4. A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked away quickly. The reason this can be done is that _____.
a. the milk carton has very little weight
b. there is an action-reaction pair operating
c. gravity pulls very hard on the milk carton
d. the milk carton has inertia
e. none of the above
5. One object has twice as much mass as another object. The first object also has twice as much _____.
a. inertia b. velocity c. gravitational acceleration d. energy e. all of the above
6. Compared to its weight on earth, a 50 kg object on the moon will weigh _____.
a. less b. more c. the same amount
7. The mass of a dog that weighs 100 N is about _____.
a. 1 kg b. 10 kg c. 100 kg d. 1000 kg e. none of the above
8. The exact mass of a dog weighing 490N is ____.
a. zero
b. 490 kg
c. 50 kg
d. 49 kg
e. none of the above
9. An object following a straight line path at constant speed _____.
a. has a net force acting on it in the direction of motion
b. has zero acceleration
c. must be moving in a vacuum
d. has no forces acting on it
e. none of the above
10. Friction _____.
a. acts in a direction that opposes the motion of an object
b. comes from microscopic bumps that act as obstructions to the objects motion
c. is the name given to the force acting between surfaces sliding past one another
d. all of the above
e. none of the above
11. A 10 N force west and a 30 N force east act on an object concurrently. What is the net force acting on the object?
a. 40 N east b. 30 N west c. 20 N east d. 20 N west e. none of the above
12. You would have the largest mass of gold if your chunk of gold weighed 1 N on _____. (THINK!!)
a. the moon b. Earth c. it doesn’t matter which planet you are on.
13. Equilibrium occurs when _____.
a. all the forces acting on an object are balanced
b. the sum of the forces acting rightward equal the sum of the forces acting leftward.
c. the sum of the forces acting upward equal the sum of the forces acting downward.
d. the net force is zero.
e. all of the above.
14. What is the maximum resultant possible when adding a 3 N force and an 8 N force?
a. 24 N b.11 N c. 8 N d. 5 N e. 3 N
15. What is the minimum resultant possible when adding a 3 N force and an 8 N force?
a. 24 N b. 11 N c. 8 N d. 5 N e. 3 N
16. Which has more mass, a kilogram of feathers or a kilogram of iron?
a. the feathers b. the iron c. same masses
17. Accelerations are produced by _____.
a. velocities b. accelerations c. forces d. masses e. none of the above
18. According to Newton’s second law, the acceleration of an object ______its mass.
a. is directly proportional to
b. is inversely proportional to
c. doesn’t depend on
19. The acceleration produced by a net force on an object is _____.
a. directly proportional the magnitude of the net force.
b. in the same direction as the net force
c. inversely proportional to the mass of the object
d. all of the above
20. Compared to its mass on earth, a 25 kg object on Jupiter will mass ____.
a. less b. more c. the same amount
21. A 10 kg brick and a 1 kg book are dropped in a vacuum. The force of gravity on the 10 kg brick is _____.
a. the same as the force on the 1 kg book
b. 10 times as much as the force on the 1 kg book
c. zero
22. An apple weighs 1 N. The net force on the apple when it is in free fall is _____.
a. 0 N b. 0.1 N c. 1 N d. 9.8 N e. none of the above
23. An apple weighs 1 N. When held at rest on top of your head, the net force on the apple is _____.
a. 0 N b. 0.1 N c. 1 N d. 9.8 N e. none of the above
24. A girls pulls a 10 kg wagon with a net force of 30 N. What is the wagon’s acceleration?
a. 0.3 m/s2 b. 3.0 m/s2 c. 10 m/s2 d. 30 m/s2 e. 300 m/s2
25. An object has a constant mass. A constant force on the object produces constant _____.
a. velocity b. acceleration c. both A and B d. none of the above
26. A force of 100 N accelerates a mass of 100 kg at the rate of 1 m/s2. The acceleration of a mass of 2 kg acted upon by a force of 2 N is _____.
a. half as much b. twice as much c. the same d. none of the above
27. A rock is thrown vertically into the air. At the top of its trajectory, the net force on it is _____.
a. less than its weight b. more than its weight c. equal to its weight
28. A block is dragged without acceleration in a straight line path across a level surface by a force of 6 N. What is the frictional force between the block and the surface?
a. less than 6 N b. more than 6 N c. 6 N d. need more information to answer
29. A tennis ball and a solid steel ball the same size are dropped at the same time. Which ball has the greater force acting on it?
a. the tennis ball b. the steel ball c. neither
30. A student hits a nail with a hammer. During the collision, there is a force _____.
a. on the hammer but not the nail
b. on the nail but not the hammer
c. on the nail and the hammer
31. Action/reaction forces always occur _____.
a. by themselves b. in pairs on the same object c. in pairs on different objects d. in triplets
32. An archer shoots an arrow. Consider the action force to be the bow string against the arrow. The reaction to this force is the ____.
a. weight of the arrow.
b. air resistance against the bow.
c. friction of the ground against the archer’s feet.
d. grip of the archer’s hand on the bow.
e. arrow’s push against the bowstring.
33. An unfortunate bug splatters against the windshield of a moving car. Compared to the acceleration of the car, the acceleration of the bug is _____.
a. larger b. smaller c. the same
34. An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is _____.
a. larger b. smaller c. the same
35. An unfortunate bug splatters against the windshield of a moving car. Which undergoes the greater change in velocity?
a. the car b. the bug c. both the same
36. A person weighs 500 N. What is the mass of the person?
W = mg so m = 500N/10m/s2
m = 50kg
37. What is the resultant of a 5.0 N force acting vertically upward and a 3 N force acting to the right? Draw a FBD, then be sure you add vectors properly.
32 + 52 = R2 tan q = 3/5
R = 5.8 N tan-1 q = 31o from vertical
38. A 200 kg bear grasping a vertical tree slides down at a constant velocity. What is the friction force between the tree and the bear? Draw a FBD.
F = W = 200kg(10 m/s2) = 2000N
39. A certain unbalanced force gives a 5 kg object an acceleration of 2.0 m/s2. What acceleration would the same force give a 30 kg object?
F = (5kg)(2m/s2) = 10N
10N = 3kg (a) a = 1/3 m/s2
40. A net force of 1.0 N acts on a 2.0 kg object, initially at rest, for 2.0 seconds. What is the distance the object moves during that amount of time?
A = F/m = 1N/2kg = 0.50 m/s2 Dd = 0 + ½ (0.5 m/s2) (2.0s)2 = 1.0 m
41. Suppose you exert 400 N horizontally on a 50 kg crate on a factory floor, when friction between the crate and the floor is 200 N. What is the acceleration of the crate? What is the coefficient of friction between the crate and the floor? Draw a FBD.
F = 400-200 = 200N
a = F/m = 200N/50kg = 4.0 m/s2
f = mN m = 200N/50kg(10m/s2) = 0.40
42. A (heavy) 50 kg block of cement is pulled upward, against gravity, with a force of 800 N. What is the acceleration of the block? Draw a FBD.
F = 800 - 500 = 300N down
a = F/m = 300N/50kg = 6.0 m/s2
43. Bronco the skydiver, whose mass is 50 kg, experiences 100 N of air resistance. What is the acceleration of his fall?
Draw a FBD.
F = -500 + 100 = -400N (down)
a = F/m = -400N/50kg = -8.0 m/s2 (down)
44. A person with a blackbelt in karate has a fist that has a mass of 0.70 kg. Starting from rest, this fist attains a velocity of 8.0 m/s in 0.15 s. What is the magnitude of the net force applied to the fist to achieve this level of performance?
a = (8.0 m/s – 0)/ 0.15s = 53 m/s2
F = ma = 0.70kg(53m/s2) = 37N