# Physics Questions

Topics: Force, Friction, Mass Pages: 7 (3151 words) Published: August 27, 2013
Old Exam. Question Ch. 5 (Dr. Gondal Phys. 101)
T082
Q15: You stand on a spring scale on the floor of an elevator. The scale shows the highest reading when the elevator: (Ans: moves downward with decreasing speed) Q16. A 70 N block A and a 35 N block B are connected by a string, as shown in Fig 3. If the pulley is massless and the surface is frictionless, the magnitude of the acceleration of the 35 N block is: A) 3.3 m/s2 Q17. When a 25.0 kg crate is pushed across a frictionless horizontal floor with a force of 200 N, directed 20◦ below the horizontal, the magnitude of the normal force of the floor on the crate is: A) 313 N T081

Q15. Two masses m1 = 10 kg and m2 = 20 kg are connected by a light string and pulled across a frictionless surface by a horizontal force F = 30 N as shown in Figure 2. Find the tension in the string. (Ans: 10 N) Q16. A 5.0-kg block and a 10-kg block are connected by a light string as shown in Figure 3. If the pulley is massless and the surface is frictionless, the magnitude of the acceleration of the 5.0 kg block is (Ans: 6.5 m/s2 Q17. A 70 kg man stands in an elevator that is moving downward at constant acceleration of 2.0 m/s2. The force exerted by the man on the elevator floor is (Ans: 546 N down)

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Fig. 3, T082 Fig. 2, T081 Fig. 3, T081 T072-Q13.Two blocks of mass m1= 24.0 kg and m2, respectively, are connected by a light string that passes over a massless pulley as shown in Fig. 2. If the tension in the string is T = 294 N. Find the value of m2. (Ignore friction) (Ans: 40.0 kg) Q14.Two horizontal forces of equal magnitudes are acting on a box sliding on a smooth horizontal table. The direction of one force is the north direction; the other is in the west direction. What is the direction of the acceleration of the box?(Ans:45° west of north) Q16.: A 5.0 kg block is lowered with a downward acceleration of 2.8m/s2 by means of a rope. The force of the block on the rope is:(Ans:35 N, down) Q17.:Two students are dragging a box (m=100 kg) across a horizontal frozen lake. The first student pulls with force F1=50.0 N, while the second pulls with force F2. The box is moving in the x-direction with acceleration a (see Fig. 3). Assuming that friction is negligible, what is F2? T071 :Q13. A constant force F of magnitude 20 N is applied to block A of mass m = 4.0 kg, which pushes block B as shown in Fig. 5. The block slides over a frictionless flat surface with an acceleration of 2.0 m/s2. What is the net force on block B? (Ans:12 N) Q14. Only two forces act upon a 5.0 kg box. One of the forces is [pic]. If the box moves at a constant velocity of [pic], what is the magnitude of the second force?( Ans: 10. N) Q15. An elevator of mass 480 kg is designed to carry a maximum load of 3000 N. What is the tension in the elevator cable at maximum load when the elevator moves down accelerating at 9.8 m/s2? (Ans: 0) Q16.: A car of mass 1000 kg is initially at rest. It moves along a straight road for 20 s and then comes to rest again. The velocity – time graph for the movement is given in Fig.6. The magnitude of the net force that acts on the car while it is slowing down to stop from t = 15 s to t = 20 s is: (Ans: 2000N)

[pic] [pic] [pic] [pic]
Fig. 3, T072 Fig. 2, T072 Fig. 5, T071 Fig. 6, T071

T062: Q15.: Two blocks of masses m1 = 4.00 kg and m2 = 2.00 kg are connected by a string passing over a massless and frictionless pulley and placed on a frictionless horizontal table as shown in Fig. 3. A force of F = 10.0 N at an angle of 60.0° with the horizontal is applied to m1. The magnitude of acceleration of the system is: (Ans: 2.43 m/s2 ) [pic][pic][pic][pic][pic]

Fig. 3, T062 Fig. 4, T062 Fig. 5, T062...