AP Physics C Multiple Choice Dynamics

1. AP Physics C Multiple Choice Dynamics

2. 1 A ball moves horizontally with an initial velocity 
v1, as shown above. It is then struck by a tennis 
racket. After leaving the racket, the ball moves 
vertically with a velocity v2, which is smaller in 
magnitude than v1. Which of the following 
vectors best represents the direction of the 
average force that the stick exerts on the ball? A <<double-click to edit>> C <<double-click to edit>> D <<double-click to edit>> B <<double-click to edit>> E <<double-click to edit>>

3. 2 A satellite is orbiting the Earth. If FE is the 
magnitude of the force exerted by the Earth on the 
satellite and FS is the magnitude of the force 
exerted by the satellite on the Earth, then which of 
the following is true? A FE is much greater than FS. B FE is slightly greater than FS. C FE is equal to FS. D FE is slightly greater than FS E FE is much greater than FS

4. 3 An object released from rest at time t = 0 slides 
down a frictionless incline 2 meters during the 
first 2 seconds. The distance traveled by the 
object during the time interval from t = 2 second 
to t = 3 seconds is approximately, A 2.5 m B 4.5 m C 9 m D 11 m E 13 m

5. 4 A marble of mass m moves along a path with a 
speed defined by the function v = bt2 + c, where t 
is time and b and c are constants. What is the 
magnitude F of the net force on the particle at 
time t = t1? A bt12 + c B 3mbt1 + 2c C mbt1 D mbt1 + c E 2mbt1

6. 5 A force F is exerted by a broom handle on the 
head of the broom, which has a mass m. The 
handle is at an angle ( to the horizontal, as shown 
above. The work done by the force on the head of 
the broom as it moves a distance d across a 
horizontal floor is A Fd sinθ B Fd cosθ C Fm cosθ D Fm tanθ E Fmd sinθ

7. 6 A body’s position as it moves on a straight path is 
given by the equation x = 2t3 3t2 + 4t, where x is 
in meters and t is in seconds. The net force on the 
body is equal to zero when t is equal to A zero B 1/2 s C 3 s D 4/5 s E 5 s

8. 7 The parabola below is a graph of speed v as a 
function of time t for an object. Which of the 
following graphs best represents the magnitude 
F of the net force exerted on the object as a 
function of time t? V A <<double-click to edit>> B <<double-click to edit>> C <<double-click to edit>> D <<double-click to edit>> E <<double-click to edit>> T

9. 8 A descending box of mass 500 kg is uniformly 
decelerated to rest over a distance of 4 m by a 
rope in which the tension is 6000 N. The speed vi 
of the elevator at the beginning of the 4 m descent 
is most nearly A 4 m/s B 10 m/s C 12 m/s D 16 m/s E 22 m/s

10. 9 When the frictionless system shown below is 
accelerated by an applied force of magnitude Fa, 
the tension in the string between the blocks is 
(A) 2 Fa (B) Fa (C) (3/5) Fa (D) (2/5) Fa 
(E) 3 Fa E <<double-click to edit>> B <<double-click to edit>> D <<double-click to edit>> C <<double-click to edit>> A <<double-click to edit>>

11. 10 Two 0.5 kilogram blocks are connected by a string 
that passes over a frictionless pulley, as shown 
below. The blocks are initially held at rest. If a third 
block with a mass of 0.25 kilograms is added on 
top of one of the 0.5 kilogram blocks as shown and 
the objects are released, the magnitude of the 
acceleration of the 0.25 kilogram object is most 
nearly A 10.0 m/s2 B 6.0 m/s2 C 4.0 m/s2 D 2.0 m/s2 E 1.0 m/s2

12. 11 A 50 newton weight is suspended by two strings 
as shown below. The tension T in the slanted 
string is A 50 N B 100 N C 150 N D 200 N E 250 N

13. 12 A rubber band ball of mass m is attached to a string 
of length R as shown below. The ball is released 
from rest from position X where the string is 
horizontal, swings through position Y where the 
string is vertical, and reaches position Z where the 
string is again horizontal. What are the directions of 
the acceleration vectors of the ball at positions Y 
and Z? Position Y   Position Z A Downward  Downward B Downward  To the right C Upward  Downward D Upward  To the left E To the right  To the left

14. 13 As shown below, two blocks are pushed along a 
horizontal frictionless surface by a 30 newton 
force to the right. The force that the 4kilogram 
block exerts on the 6kilogram block is A 8 newtons to the left B 8 newtons to the right C 10 newtons to the left D 12 newtons to the left E 12 newtons to the right

15. 14 A mass m moves on a curved path from point X to 
point Y. Which of the following diagrams indicates 
a possible combination of the net force F on the 
mass, and the velocity v and acceleration a of the 
mass at the location shown? A E C B D

16. 15 Two identical massless springs are hung from the 
ceiling. The springs suspend a block of mass 2.4 
kg, as shown below. When the block is in 
equilibrium, each spring is stretched an additional 
0.3 meters. The force constant of each spring is 
most nearly:  (A) 40 N/m (B) 48 N/m (C) 60 N/m (D) 80 N/m (E) 96 N/m A <<double-click to edit>> B <<double-click to edit>> E <<double-click to edit>> C <<double-click to edit>> D <<double-click to edit>>

17. 16 A 10 kilogram block lies on an inclined plane. 
The incline is 8 meters wide and 6 meters tall. 
The coefficient of friction between the plane and 
the block is 0.3. The magnitude of the force F 
necessary to move the block up the plane with 
constant speed is most nearly A 64 N B 76 N C 82 N D 90 N E 108 N

18. 17 A figure of a dancer on a music box moves 
counterclockwise at constant speed around the 
path shown above. The path is such that the 
lengths of its segments, WX, XY, YZ, and ZW, are 
equal. Arcs WX and YZ are semicircles. Which of 
the following best represents the magnitude of the 
dancer's acceleration as a function of time t 
during one trip around the path, beginning at 
point W ? A B C D E

19. 18 A ball is released from rest at time t = 0 and falls in 
the presence of air, which exerts a resistant force. 
The acceleration a of the ball is given by a = g - bv, 
where v is the object's velocity and b is a constant. 
If limiting cases for large and small values of t are 
considered, which of the following is a possible 
expression for the speed of the object as an 
explicit function of time? A v = g(1-e-bt)/b B V = (geht)/b C v = gt - bt2 D v = (g + a)t/b E v = v0+ gt, v0 ≠ 0

20. 19 As shown above, a block of mass m is pulled 
across a rough surface by a force F exerted at 
an angle Θ with the horizontal. The frictional 
force on the block exerted by the surface has 
magnitude f. What is the acceleration of the block? A F/m B FcosΘ /m C (F-f)/m D (FcosΘ-f)/m E (FsinΘ-mg)/m

21. 20 As shown above, a block of mass m is pulled 
across a rough surface by a force F exerted at an 
angle Θ with the horizontal. The frictional force 
on the block exerted by the surface has 
magnitude f. What is the coefficient of friction between the 
block and the surface? A f/mg B mg/f C (mg-FcosΘ)/f D f/(mg-FcosΘ) E f/(mg-FsinΘ)

22. 21 A 10 kg object moves according to the function: x=
3t2-4t+7. Which of the following represents the net force that acts on the object? A 52 N B 60N C 67 N D 78 N E 84 N

23. Questions 22-25 The system above consists of three blocks, m1, m2 and m3 where m1 and m2 are attached to a virtually massless cord and m3 sits on top of m1. The system is attached to a massless pulley and accelerates downward. 
There is no friction between the surface and m1 however there is friction between the m1 and m3. The coefficient of kinetic friction is µ however the coefficient of static friction is not given. Block m3 does not slide off of block m1. 22 Find the acceleration of m2 A m1g/(m2+m3) B (m1+m2+m3)/m2g C m2g/(m1+m2+m3) D (m1+m3)g/m2 E (m1+m3)/m2g

24. 23 What coefficient of static friction must there be in 
order for m3 not to slide off of block m1? A m2/(m1+m2+m3) B m1/(m2+m3) C (m1+m3)/m2 D (m1+m2+m3)/m2 E m3/(m1+m2+m3)

25. 24 Find the acceleration of block m3. A µg(m1+m2+m3)/m3 B µm3g/m1 C µg D µg(m1+m3)/m2 E µgm3/(m1+m2+m3)

26. 25 What is the acceleration of block m2? A (m2-µm3)g/(m1+m2) B m2g/µ(m1+m3) C (m1+m2+m3)µ/3m1g D (m1+m3) µg E (m1+m3)g/µ(m1+m2+m3)

27. 26 A ball of mass m falls in the presence of air 
resistance. The resistive force is represented by 
F=bv2 where b is a constant and v represents the 
ball’s velocity. The acceleration of the ball is 
most nearly A (mg)/v B b-g C (g-bv2)/m D (bv+g)/m E bvg

28. 27 A rubber band ball is suspended by two strings 
of unequal lengths. Which of the following is true 
about T1 and T2 in the strings? A T1< T2 B T1> T2 T2 T1 C T1= T2 D T1- T2=mg E (T1+T2)sinѲ=mg

29. 28 Questions 28-30 A 60 newton force is pushing a 5 kg box is being 
pushed up an incline at a 53° angle (cos53°=0.6, 
sin53°=0.8). The coefficient of kinetic friction is 
0.5. Which diagram best represents the block’s weight 
W, normal force Fn and the friction force Fr on the 
block? C A B A B E D C D E

30. 29 The normal force on the block is A 10 N B 20 N C 30 N D 40 N E 50 N

31. 30 Calculate the block’s acceleration as it moves up 
the incline A 0.5 m/s2 B 1.0 m/s2 C 2.9 m/s2 D 3.5 m/s2 E 4.2 m/s2

32. 31 A truck of mass 5m collides head on with a car of 
mass 3m. FT represents the force the truck 
applies to the car. FC represents the force the car 
applies to the truck. Which of the following is 
true? A FT> FC B FT<FC C FT=FC D 3FT=5FC E 5FT=3Fc

33. 32 A car is traveling with velocity v and sees a kid 
playing with a ball in the street. The driver slams 
on the brakes with a force F and stops in time for 
the kid to move away safely. If the car was 
traveling twice as fast how much force would be 
required to stop at the same spot? A F/4 B F/2 C F D 2F E 4F

34. 33 A 30 kg block and 10 kg block are set up 
on an incline plane using a pulley system 
(Friction is not negligible). The 30 kg block 
accelerates downward while the 10 kg 
block is accelerating up the incline. The 
acceleration is equal to 2m/s2 Determine the tension in the string. A 200 N B 210 N C 220 N D 230 N E 240 N

35. 34 A 30 kg block and 10 kg block are set up on an 
incline plane using a pulley system (Friction is not 
negligible). The 30 kg block accelerates downward 
while the 10 kg block is accelerating up the incline. 
The acceleration is equal to 2m/s2 Determine the friction force acting on the 10 kg 
block. A 75 N B 100 N C 140 N D 160 N E 175 N