# AP Physics C Multiple Choice Dynamics.

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AP Physics C Multiple Choice Dynamics

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>> B D E <<double-click to edit>> <<double-click to edit>> <<double-click to edit>>

FE is much greater than FS.
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

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

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

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

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

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

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

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 B E <<double-click to edit>> <<double-click to edit>> D <<double-click to edit>> C <<double-click to edit>> A <<double-click to edit>>

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

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

12 Downward Downward Downward To the right Upward Downward
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

13 8 newtons to the left 8 newtons to the right 10 newtons to the left
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

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 B C D E

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>>

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

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

18 v = g(1-e-bt)/b V = (geht)/b v = gt - bt2 v = (g + a)t/b
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

What is the acceleration of the block?
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

20 f/mg mg/f (mg-FcosΘ)/f f/(mg-FcosΘ) f/(mg-FsinΘ)
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)

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

22 m1g/(m2+m3) (m1+m2+m3)/m2g m2g/(m1+m2+m3) (m1+m3)g/m2 (m1+m3)/m2g A
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

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)

Find the acceleration of block m3.
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)

What is the acceleration of block m2?
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)

26 (mg)/v b-g (g-bv2)/m (bv+g)/m bvg
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

27 T1< T2 T1> T2 T1= T2 T1- T2=mg (T1+T2)sinѲ=mg
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 C T1= T2 T1 D T1- T2=mg E (T1+T2)sinѲ=mg

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 D E C D E

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

Calculate the block’s acceleration as it moves up the incline
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

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

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

Determine the tension in the string.
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

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