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Newton’s Laws and Their Applications Review
AP Physics
Part I. Conceptual Multiple Choice.
1.) A satellite is in orbit around the earth. Which one feels the greater force?
(A) The satellite because the earth is so much more massive
(B) The earth because the satellite has so little mass
(C) Earth and the satellite feel exactly the same force.
(D) It depends on the distance of the satellite from Earth.
2.) You are in a train traveling on a horizontal track and notice that a piece of
luggage starts to slide directly toward the front of the train. From this
observation, you can conclude that this train is
(A) speeding up.
(B) slowing down.
(C) changing direction.
(D) speeding up and changing direction.
(E) slowing down and changing direction.
3.) A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s.
The vector sum of all the forces acting on this crate must point
(A) down the ramp.
(B) up the ramp.
(C) perpendicular to the ramp.
(D) vertically downward.
(E) None of the above choices is correct.
4.) You push on box G that is next to box H, causing both boxes to slide
along the floor, as shown in the figure. The reaction force to your
push is
(A) the push of box G on box H.
(B) the push of box H on box G.
(C) the push of box G against you.
(D) the upward force of the floor n box G.
(E) the acceleration of box G.
5.) An object is moving with constant non-zero velocity. Which of the
following statements about it must be true?
(A) A constant force is being applied to it in the direction of motion.
(B) A constant force is being applied to it in the direction opposite of
motion.
(C) A constant force is being applied to it perpendicular to the direction
of motion.
(D) The net force on the object is zero.
(E) Its acceleration is in the same direction as its velocity.
6.) The figure shows two boxes, with m1 > m2, that are on a level frictionless
surface. We can apply a horizontal force F either toward the right on m1
or toward the left on m2. The magnitude of the force that the boxes exert
on each other is
(A) zero Newtons in either case.

(B) larger if F is applied toward the right.

(C) larger if F is applied toward the left.
(D) the same in either case.
7.) You are standing in a moving bus, facing forward, when you suddenly
slide forward as the bus comes to an immediate stop. What force caused
you to slide forward?
(A) gravity
(B) the normal force due to your contact with the floor of the bus
(C) the force due to friction between you and the floor of the bus
(D) There is not a force causing you to slide forward.
8.) The acceleration due to gravity is lower on the Moon than on Earth. Which
one of the following statements is true about the mass and weight of an
astronaut on the Moon's surface, compared to Earth?
(A) Mass is less, weight is the same.
(B) Mass is the same, weight is less.
(C) Both mass and weight are less.
(D) Both mass and weight are the same.
9.) Inside of a train a ball of weight W is hanging by a light wire at rest from
the ceiling. The wire makes an angle θ with the ceiling, as shown in the
figure. Which one of the following conditions must be true about the
tension T in the wire?
(A) T sin θ = W
(B) T cos θ = W
(C) T tan θ = W
(D) T = W
(E) T = ma
10.) Two blocks, A and B, are being pulled to the right along a horizontal
surface by a horizontal 100-N pull, as shown in the figure. Both of them
are moving together at a constant velocity of 2.0 m/s to the right, and
both weigh the same.
Which of the figures below shows a correct free-body diagram of the
horizontal forces acting on the upper block, A?
A)
B)
C)
D)
E)
11.) A person who normally weighs 700 N is riding in a rather swift elevator
that is moving at a constant speed of 9.8 m/s. If this person is standing on
a bathroom scale inside the elevator, what would the scale read?
(A) more than 700 N
(B) less than 700 N
(C) 700 N
(D) It could be more or less than 700 N, depending on whether the
elevator is going up or down.
Part II. Computational Multiple Choice.
12.) If I weigh 741 N on Earth at a place where g = 9.80 m/s2 and 5320 N on
the surface of another planet, what is the acceleration due to gravity on
that planet?
(A) 70.4 m/s2
(B) 51.4 m/s2
(C) 61.2 m/s2
(D) 81.0 m/s2
13.) If a net force accelerates a 4.5-kg tool at 40 m/s2, what acceleration would
that same net force give to an 18-kg tool?
(A) 180 m/s2
(B) 10 m/s2
(C) 160 m/s2
(D) 9.8 m/s2
(E) 32 m/s2
14.) A block is on a frictionless table, on earth. The block accelerates at
3.0 m/s2 when a 20 N horizontal force is applied to it. The block and
table are set up on the Moon where the acceleration due to gravity is
1.62 m/s2. The weight of the block on the Moon is closest to
(A) 11 N.
(B) 9.5 N.
(C) 8.1 N.
(D) 6.8 N.
(E) 5.5 N.
15.) A 450-kg sports car accelerates from rest to 100 km/h in 4.80 s. What
magnitude force does a 68.0 kg passenger experience during the
acceleration?
(A) 394 N
(B) 82.0 N
(C) 342 N
(D) 311 N
16.) An object that weighs 75 N is pulled on a horizontal surface by a
horizontal pull of 50 N to the right. The friction force on this object is 30
N to the left. What is the acceleration of the object?
(A) 0.27 m/s2
(B) 1.1 m/s2
(C) 2.6 m/s2
(D) 11 m/s2
17.) A 1200-kg car is pulling a 500-kg trailer along level ground. Friction of
the road on the trailer is negligible. The car accelerates with an
acceleration of 1.3 m/s2. What is the force exerted by the car on the trailer?
(A) 550 N
(B) 600 N
(C) 650 N
(D) 700 N
(E) 750 N
18.) The figure shows an acceleration-versus-force graph for a 125-g object.
What should be the value of the first tick-mark on the vertical scale, as
indicated by the arrow in the figure?
(A) 4
(B) 8
(C) 0.00400
(D) 0.00800
19.) A push of magnitude P acts on a box of weight W as shown in the figure.
The push is directed at an angle θ below the horizontal, and the box remains
a rest. The box rests on a horizontal surface that has some friction with the
box. The normal force on the box due to the floor is equal to
(A) W.
(B) W + P.
(C) W + P cos θ.
(D) W + P sin θ.
(E) W - P sin θ.
20.) Two objects have masses m and 5m, respectively. They both are placed
side by side on a frictionless inclined ramp and allowed to slide down
from rest without any air resistance. Which one of the following
statements about these objects is correct?
(A) It takes the lighter object 5 times longer to reach the bottom of the
ramp than the heavier.
(B) It takes the lighter object 10 times longer to reach the bottom of the
ramp than the heavier.
(C) It takes the heavier object 5 times longer to reach the bottom of the
ramp than the lighter.
(D) It takes the heavier object 10 times longer to reach the bottom of the
ramp than the lighter.
(E) The two objects reach the bottom of the ramp at exactly the same
time.
21.) A block of mass m sits at rest on a rough inclined ramp that makes an
angle θ with the horizontal. What must be true about force of static
friction f on the block?
(A) f > mg
(B) f > mg cos θ
(C) f > mg sin θ
(D) f = mg cos θ
(E) f = mg sin θ
22.) A 50.0-kg crate is being pulled along a horizontal smooth surface. The
pulling force is 10.0 N and is directed 20.0° above the horizontal. What is
the magnitude of the acceleration of the crate?
(A) 0.0684 m/s2
(B) 0.188 m/s2
(C) 0.200 m/s2
(D) 0.376 m/s2
(E) 0.0728 m/s2
23.) A 400-kg box is lifted vertically upward with constant velocity by means
of two cables pulling at 40.0° on either side of the vertical direction. What
is the tension in each cable?
(A) 231 N
(B) 400 N
(C) 800 N
(D) 2560 N
(E) 3920 N
24.) A 10-kg sign is held by two ropes as shown in the figure. What is the
tension on rope A?
(A) 44 N
(B) 69 N
(C) 72 N
(D) 88 N
(E) 98 N
25.) A policeman investigating an accident measures the skid marks left by a
car on the horizontal road. He determines that the distance between the
point that the driver slammed on the brakes (thereby locking the wheels)
and the point where the car came to a stop was 28.0 m. From a reference
manual he determines that the coefficient of kinetic friction between the
tires and the road under the prevailing conditions was 0.300. How fast
was the car going when the driver applied the brakes?
(A) 10.7 m/s
(B) 12.8 m/s
(C) 21.4 m/s
(D) 32.9 m/s
(E) 45.7 m/s
26.) A 50-kg box is resting on a horizontal floor. A force of 250 N directed at
an angle of 30.0° below the horizontal is applied to the box. The
coefficient of static friction between the box and the surface is 0.40, and
the coefficient of kinetic friction is 0.30. What is the force of friction on
the box?
(A) 32 N
(B) 200 N
(C) 220 N
(D) 250 N
(E) 620 N
27.) A driver in a 1000 kg car traveling at 24 m/s slams on the brakes and skids
to a stop. If the coefficient of friction between the tires and the level road
is 0.80, how long will the skid marks be?
(A) 37 m
(B) 30 m
(C) 46 m
(D) 34 m
28.) You push downward on a trunk at an angle 25° below the horizontal with
a force of 750 N. If the trunk is on a flat surface and the coefficient of
static friction between the surface and the trunk is 0.61, what is the most
massive trunk you will be able to move?
(A) 81 kg
(B) 93 kg
(C) 73 kg
(D) 112 kg
29.) A 45.0-kg person steps on a scale in an elevator. The scale reads
460 N. What is the magnitude of the acceleration of the elevator?
(A) 4.91 m/s2
(B) 9.81 m/s2
(C) 46.9 m/s2
(D) 0.206 m/s2
(E) 0.422 m/s2
Part III. Word Problems
30.) A 40-kg crate is being lowered with a downward acceleration is 2.0 m/s2
by means of a rope.
a.) What is the magnitude of the force exerted by the rope on the crate?
b.) What would be the magnitude of the force exerted by the rope if the
crate were being raised with an acceleration of 2.0 m/s2?
31.) A box of mass 72 kg is at rest on a horizontal frictionless surface. A
constant horizontal force of magnitude F then acts on the box, accelerating
it to the right. You observe that it takes the box 3.4 seconds to travel 13
meters. What is the magnitude of the force F?
32.) A 958-N rocket is coming in for a vertical landing. It starts with a
downward speed of 25 m/s and must reduce its speed to 0 m/s in 8.0 s for
the final landing.
a.) During this landing maneuver, what must be the thrust due to the
rocket's engines?
b.) What must be the direction of the engine thrust force?
33.) A 10-kg object is hanging by a very light wire in an elevator that is
traveling upward. The tension in the rope is measured to be 75 N.
What are the magnitude and direction of the acceleration of the elevator?
34.) The figure shows a block of mass M hanging at rest. The light wire
fastened to the wall is horizontal and has a tension of 38 N. The wire
fastened to the ceiling is also very light, has a tension of 59 N and
makes an angle θ with the ceiling. Find the angle θ.