SECTION A – Linear Dynamics - Zphysics

1 AP Physics Multiple Choice Practice DynamicsSECTION A Linear ball of massm is suspended from two stringsof unequal length as shown above. Themagnitudes of thetensions T1and T2in the strings must satisfy which of the following relations?(A) Tl= T2(B) T1> T2(C) T1< T2(D) Tl+ T2= mgQuestions2 3A 2-kgblock slides down a 30 incline as shown above with an acceleration of 2 of the following diagrams best represents the gravitational force W. the frictional force f, and the normalforce N that act on the block? of the following correctly indicates the magnitudes of the forces acting up and down theincline?

2 (A)20 N down the plane, 16 N up the plane(B)4 N down the plane, 4 N up the plane(C)0 N down the plane, 4 N up the plane(D)10 N down the plane, 6 N up the the frictionless system shown above is accelerated by an applied force of magnitudethe tension in thestring between the blocks is (A) F (B)2/3F (C) F (D)1 ball falls straight down through the air under the influence of gravity. There is a retarding force F on the ballwith magnitude given by F =bv, wherevis the speed of the ball andbis a positive ball reaches aterminal velocity after a magnitude of the accelerationat timet/2 is(A)Increasing(B)Decreasing(C)10 m/s/s(D)Zero(D) block of weight W is pulled along a horizontal surface at constant speed v by a force F, which acts at an angleof with the horizontal, as shown above.

3 The normal force exerted on the block by the surface has magnitude(A)greater than W(B)greater than zerobut less than W(C)equal to W(D) uniform rope of weight 50 Nhangs from a hook as shown above. A box of weight 100 Nhangs from therope. What is the tension in the rope ?(A) 75 N throughout the rope (B) 100 N throughout the rope (C) 150N throughout the rope (D) It varies from 100 N at the bottom of the rope to 150 N at the an object of weight W is suspended from the center of a massless string as shown above,the tension atany point in the string is(A) 2 Wcos (B) Wcos (D) W/(2cos ) (E) W/(cos ) block of mass 3m can move without friction on a horizontal table.

4 This block is attached to another block ofmass m by a cord that passes over a frictionless pulley, as shown above. Ifthe masses of the cord and the pulleyare negligible, what is the magnitude of the acceleration of the descending block?(A) g/4 (B) g/3 (C) 2g/3 (D) g40A plane 5 meters in length is inclined at an angle of 37 , as shown above. A block of weight 20 Nis placed atthe top of the plane and allowed to slide magnitude of the normal force exerted on the block by the plane is(A) greater than20 N(B) greater than zero but less than 20 N(C) equal to 20 N(D) correct:Three forces act on an object.

5 If the object ismoving to the rightin translational equilibrium,which of the following must be true?Selecttwo answers.(A)The vector sum of the three forces must equal zero.(B) All three forces must be parallel.(C)The magnitudes of the three forces must be equal.(D) The object must be moving at a constant which of the following motions of anobject must the acceleration always be zero?(A)Any motion in a straight line(B)Simple harmonic motion(C)Any motionat constant speed(D) Anysingle object inmotionwith constant rope of negligible mass supports a block thatweighs 30 N, as shown above.

6 The breaking strength of therope is 50 N. The largest acceleration that can be given to the block by pulling up on it with the rope withoutbreaking the rope is most nearly(A) m/s2(B)10 m/s2(C) m/s2(D) m/s2 Questions 14-15A horizontal, uniform board of weight 125 N and length 4 m is supported by vertical chains at each end. Aperson weighing 500 N is hanging from the board. The tension in the right chain is 250 isthe tension in the left chain?(A) 125 N (B) 250 N (C) 375 N (D) 625 of the following describes where the person is hanging?

7 (A) between the chains, but closer to the left-hand chain(B) betweenthe chains, but closer to the right-hand chain(C) Right in the middle of the board(D) directly below one of the correct:The cart of mass 10 kg shown above moves without frictional loss on a level table. A 10 Nforce pulls on the cart horizontally to the right. At the same time, a 30 N force at an angle of 60 above thehorizontal pulls on the cart to the of thefollowing describes a manner in which this cart could bemoving?Selecttwo answers.(A)moving left and speeding up(B)moving left and slowing down(C)moving right and speeding up(D)moving right and slowing people are pulling on the ends of a person pulls with a force of 100 N.

8 The tension in the ropeis:(A) 0 N (B) 50 N (C) 100 N (D) 200 parabola above is a graph of speed v as a function of time t for an object. Which of the following graphsbest represents the magnitude F of the net force exerted on the object as a function of time t?(A)(B)(C)(D) ball initially moves horizontally with velocity vi, as shown above. It is then struck by a stick. After leavingthe stick, the ball moves vertically with a velocity vf, which is smaller in magnitude than vi. Which of thefollowing vectors best represents the direction of the average force that the stickexerts on the ball?

9 Massless springs, of spring constantsk1andk2,are hung from a horizontal support. A block ofweight 12 Nis suspended from the pair of springs, as shown above. When the block is in equilibrium, each spring isstretched an additional24 , the equivalent spring constant of the two-spring system is 12 N / 24 cm = N/cm. Which of the following statements is correct aboutk1andk2?(A)k1=k2= N/cm(B) 1/k1+ 1/k2= 1/( N/cm)(C)k1 k2= N/cm(D)k1+k2= ball is thrown and follows a parabolic path, as shown above. Air friction is negligible. Point Q is the highestpoint on the path.

10 Which of the following best indicates the direction of the net force on the ball at point P ?(A)(B)(C)(D) block of mass m is accelerated across a rough surface by a force of magnitude F that is exerted at an angle with the horizontal, as shown frictional force on the block exerted by the surface has is the acceleration of the block?(A) F/m(B)(Fcos )/m (C) (F f)/m(D) (Fcos f) blocks of masses 3m, 2m, andsare connected to stringsA, B, andCas shown above. The blocks arepulled along a rough surface by a force of magnitudeFexerted by stringC.