PSI AP Physics C Dynamics Multiple Choice Questions

PSI AP Physics C – DynamicsMultiple Choice Questions1. After firing a cannon ball, the cannon moves in the opposite direction from the ball.This an example of:(A)Newton’s First Law(B)Newton’s Second Law(C)Newton’s Third Law(D)Newton’s Law of Gravitation(E)None of the above2. In the absence of an external force a moving object will(A) slow down and come to a stop(B) speed up(C) move with a constant speed in a straight line(D) turn to the right(E) turn to the left3. A loaded truck collides with a car causing a large amount of damage to the car. Whichof the following is true about the collision?(A)The force on the truck is greater than the force on the car.(B)The force on the car is greater than the force on the truck.(C)The force on the truck is the same in magnitude as the force on the car.(D)During the collision, the truck has a greater displacement than the car.(E)During the collision, the truck has a greater acceleration than the car.4. An object is thrown straight up. How do we compare the net force on the object to itsweight when it is at the highest point in the path?(A)It is greater than the weight(B)It is slightly less than the weight(C)It is zero(D)It is equal to the weight(E)It can’t be determined

5. An elevator car weighs 5500 N. If the car accelerates upwards at a rate of 4.0 m/s2,what is the tension in the support cable lifting the car? Use g 10 m/s 2.(A) 1600 N(B) 3300 N(C) 4400 N(D) 7700 N(E) 8700 N6.Which of the following diagrams best represents the gravitational force W, the frictional force f,and the normal force N that act on the block sliding down the inclined plane as shown above?A.B.C.D.E.7. A block with a mass m 5 kg slides down an inclined plane with an angle θ 37 . Theblock maintains a constant acceleration a 5.6 m/s2. (sin37 0.6, cos37 0.8). Thecoefficient of kinetic friction between the block and the inclined surface is 0.05. What isthe normal force on the block?(A) 50 N(B) 40 N(C) 30 N(D)20 N(E) 10 N

8. A block with a mass m 5 kg slides down an inclined plane with an angle θ 37 . Theblock maintains a constant acceleration a 5.6 m/s2. (sin37 0.6, cos37 0.8). Thecoefficient of kinetic friction between the block and the inclined surface is 0.05. What isthe friction force between the block and inclined plane?(A) 2 N(B) 5 N(C) 6 N(D) 30 N(E) 40 N9. The coefficient of static friction between the block and the inclined plane is 0.4 andθ 250. The block is placed on the inclined plane. The block will:(A) not move.(B) start moving down the incline and then stop before it reaches the bottom of theincline.(C) start moving down the incline and continue to increase its velocity.(D) start moving and increase its acceleration until it reaches the bottom of theincline.(E) start moving and then its acceleration will decrease.

10. A system of two blocks is accelerated by an applied force of magnitude F on thefrictionless horizontal surface. The tension in the string between the blocks is:(A) 3F(B) 5F(C) 3/8 F(D) 1/3 F(E) 1/5 F11. A student pulls a wooden box along a rough horizontal floor at constant speed by meansof a force P as shown to the right. Which of the following must be true?(A) P f and N W.(B) P f and N W.(C) P f and N W.(D) P f and N W.(E) P f and N W.12. As shown below, a boy pushes a sled of massm across a rough horizontal surface byapplying a force of magnitude F directed atan angle . The normal force on the sled is:(A) mg(B) mg sin (C) mg cos (D) mg F sin (E) mg – F sin 13. A block of mass m is pulled along a horizontal surfaceat constant speed v by a force Fapp , which acts at anangle of with the horizontal. The normal forceexerted on the block by the surface is:

(A) mg - Fapp cos (B) mg- Fapp sin (C) mg(D) mg Fapp sin (E) mg Fapp cos 14. An ideal spring obeys Hooke's law, F -kx. A mass of 0.30 kg hung vertically from thisspring stretches the spring 0.015 meter. The value of the spring constant is nearly(A) 150 N/m(B) 200 N/m(C) 300 N/m(D) 250 N/m(E) 350 N/m15. A block with a mass m is placed on the top of an identicalblock m and the system of two blocks is at rest on a roughhorizontal surface as shown below. The top block is tied tothe wall. The coefficient of static friction between allsurfaces is µs. What maximum value does force F reachbefore the lower block starts sliding to the left?(A) 3 µsmg(B) 2 µsmg(C) 4 µsmg(D) ½ µsmg(E) ¼ µsmg16. Three blocks connected with each other by two light strings. The blocks have differentmasses m2 m3 m1. The heaviest of three blocks is placed on a frictionless table. Thesystem of three blocks is released from rest. What is the acceleration of block m2?(A) (A)(m2 - m3 - m1)g/(m1 m2 m3)(B) (B)(m1 - m3 - m2)g/(m1 m2 m3)(C) (C)(m3 - m1)g/(m1 m2 m3)(D) (D)(m3 - m2- m1)g/(m1 m2 m3)(E) (E)(m1 - m3)g/(m1 m2 m3)

17. A lamp of mass m is suspended from two cables of unequallength as shown to the right. Which of the following is trueabout the tensions T1 and T2 in the cables?(A) Tl T2(B) T1 T2(C) T2 T1(D) Tl - T2 mg(E) Tl T2 mg18. A ball of mass m is suspended from two massless strings of anequal length as shown below. The tension force in each string is:(A) ½ mgcos (B) 2mgcos (C) mgcos (D) mg/(cos )(E) mg/(2cos )19. A ball moves horizontally with an initial velocity vo, as shown above. It is then struck by atennis racket. After leaving the racket, the ball moves with a velocity v. Which of thefollowing vectors best represents the direction of the average force that the racketexerts on the ball?(A)(B)(C)(D)(E)

20. 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 onthe particle at time t t1?(A) bt1 2 c(B) 3mbt1 2c(C) mbt1(D) mbt1 c(E) 2mbt121. The position as a function of time of a moving object is given by the formulax 2t3 – 3t2 4t. At what time the net force on the object is zero?(A) 0.5 s(B) 1.0 s(C) 1.5 s(D) 1.8 s(E) 2.2 s22. The velocity as a function of time of a moving object is shown by the graph. Which ofthe following graphs best represents the magnitude of the net force exerted on theobject as a function of time?(A)(B)(B)(D)(E)

23. A box of 50 kg is pulled up from rest by a cable. The tension force in the cable is 600 N.What is the box’s velocity after it covers vertical distance of 16 m?(A) 4 m/s(B) 8 m/s(C) 12 m/s(D) 16 m/s(E) 20 m/s24. An Atwood machine is presented by the diagram. What is the magnitude of theacceleration of 0.5 kg block?(A) 6 m/s2(B) 4 m/s2(C) 2 m/s2(D) 1 m/s2(E) 0.5 m/s225. A 12 kg sphere is supported by two ropes AB and BC. What is the tension force in ropeBC?(A) 120 N(B) 160 N(C) 180 N(D) 200 N(E) 240 N

26. A 12 kg sphere is supported by two ropes AB and BC. What is the tension force in ropeAB?(A) 120 N(B) 160 N(C) 180 N(D) 200 N(E) 240 N27. A small sphere is attached to a light string that can move in a vertical circle. The sphereis released from point 1 and describes a semicircle when it reaches point 2. What arethe directions of the acceleration vector at point 1 and point 2?Point 1Point 2(A) DownwardUpward(B) DownwardTo the right(C) UpwardUpward(D) To the rightUpward(E) To the rightDownward

28. A particle moves along a curved path from point 1 to point 2. Which of the followingdiagrams indicates a possible combination of the net force, acceleration and velocity ofthe particle?(A)(B)(C)(D)(E)29. A 12 kg block is suspended from two light, identical springs. When the block is inequilibrium the springs stretch by 30 cm. What is the spring constant of each spring?(A) 50 N/m(B) 100 N/m(C) 120 N/m(D) 160 N/m(E) 200 N/m30. What minimum force is required to move 10 kg block up the inclined plane with anangle of 37 above the horizontal? The coefficient of kinetic friction between the blockand the inclined surface is 0.2.(A) 76 N(B) 54 N(C) 42 N(D) 36 N(E) 28 N

31. A sphere of mass m falls in the presence of air resistance. If the air resistance force isgiven F -bv and at time t 0 vo 0, which of the following expressions is the velocity ofthe sphere as a function of time?(A) V 𝑚𝑔𝑏𝑏𝑏𝑚(1 - 𝑒 𝑚𝑡 ) (B) V 𝑏 (1 - 𝑒 𝑚𝑡 )𝑏𝑏(D) V 𝑚𝑔(1 - 𝑒 𝑚𝑡 )(E) V 𝑚𝑔𝑏𝑔𝑏(C) V 𝑏 (1 - 𝑒 𝑚𝑡 )𝑚(1 - 𝑒 𝑏 𝑡 )32. In the physics lab, a student performs an experiment with a double-sided spring gun.When the spring is compressed and then released it can fire two rubber balls m 1 and m2at the same time. From this experiment the student was able to measure only theacceleration of each ball a1 and a2. Based on this information, which of the following canbe determined?(A) m1 and m2 only(B) Spring force F only(C) Spring Force F, m 1 and m2(D) Ratio of m1 and m2 only(E) Ratio of m1 and m2, and spring force F only33. A block of mass m moves with acceleration, a, down a frictionless inclined plane thatmakes an angle Ɵ with the horizontal. Which of the following expressions about thenormal force on the block is correct?(A) Fn mg(B) Fn mg sinƟ(C) Fn mg cosƟ(D) Fn ma(E) Fn mg tanƟ

34. A block of mass m moves with acceleration, a, down a frictionless inclined plane thatmakes an angle Ɵ with the horizontal. Which of the following expressions about theacceleration of the block is correct?(A) a g(B) a g sinƟ(C) a g cosƟ(D) a 2g(E) a g tanƟ35. A block slides at a constant velocity down the inclined plane that makes an angle Ɵ withthe horizontal. Which of the following expressions represents the coefficient of kineticfriction between the block and the inclined surface?(A) tanƟ(B) sinƟ(C) cosƟ(D)1𝑡𝑎𝑛Ɵ1(E)𝑠𝑖𝑛Ɵ36. An object of mass 1 kg starts from rest and moves along a straight line. The velocity as afunction of time is given v 3t2 2t. What is the instantaneous force on the object attime t 3 s?(A) 10 N(B) 20 N(C) 30 N(D) 40 N(E) 50 N37. A 10 kg box is pushed with an initial velocity of 4 m/s on a horizontal surface. The boxmoves 8 m before it comes to a complete stop. What is the coefficient of kinetic frictionbetween the box and the surface?(A) 0.30(B) 0.20(C) 0.10(D) 0.05(E) 0.02

38. A 10 kg block is place on top of the 20 kg block as shown. The system of two blocks canmove on a horizontal frictionless surface. The coefficient of static friction between theblocks is 0.6. If a horizontal 150 N force is applied to the 20 kg block and the top blockdoesn’t slide on the bottom block, what is the acceleration of the system?(A) 1 m/s2(B) 3 m/s2(C) 5 m/s2 (D) 7 m/s2 (E) 9 m/s239. A 10 kg block is place on top of the 20 kg block as shown. The system of two block canmove on a horizontal frictionless surface. The coefficient of static friction between theblocks is 0.6. If a horizontal 150 N force is applied to the 20 kg block and the top blockdoesn’t slide on the bottom block, what is the magnitude of the horizontal force thatthe 10 kg block exerts on the 20 kg block?(A) 10 N (B) 20 N(C) 30 N(D) 50 N(E) 60 N40. A block is given an initial velocity vo when it is at the bottom of a rough inclined plane.Which of the following is true about the block as it moves?(A) It has the same acceleration as it moves up and down the plane.(B) It has greater acceleration as it moves up the plane and less acceleration as itmoves down the plane.(C) It has greater acceleration as it moves down the plane and less acceleration as itmoves up the plane.(D) It has a varying acceleration as it moves up and down the plane.(E) It has a constant velocity as it moves up and down the plane.

Answer 40.B

After firing a cannon ball, the cannon moves in the opposite direction from the ball. This an example of: (A)Newton’s First Law . tennis racket. After leaving the racket, the ball moves with a velocity v. Which of the . When the spring is compressed and then released it can fire two rubber balls m 1 and m 2