17
ANDHERI / BORIVALI / DADAR / CHEMBUR / THANE / MULUND/ NERUL / POWAI TOPICS: LAWS OF MOTION& FRICTION SECTION-I This section contains 10multiple choice questions. Each question has 4 choices (A), (B), (C) and (D) for its answer, out which ONLY ONE is correct. 1.The tension T in the thread shown in fig is Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

LOM Assignment

Embed Size (px)

DESCRIPTION

This makes sense!

Citation preview

Page 1: LOM Assignment

ANDHERI / BORIVALI / DADAR / CHEMBUR / THANE / MULUND/ NERUL / POWAI

TOPICS: LAWS OF MOTION& FRICTION

SECTION-I

This section contains 10multiple choice questions. Each question has 4 choices (A), (B), (C) and (D) for its answer, out which ONLY ONE is correct.

1. The tension T in the thread shown in fig is

(a) 10 N (b) zero (c) 98 N (d) 196 N

2. A body of weight 50 N is in equilibrium on a horizontal

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 2: LOM Assignment

surface with a force of 28.2 N. The frictional force acting on the body and the normal force will be (a) 2N, 3N (b) 5N, 7N(c) 10 N, 15 N (d) 20 N, 30 N

3. Three blocks of masses 3 kg, 6 kg and 1 kg are connected by a string passing over two smooth pulleys attached at the two ends of a frictionless horizontal surface. The acceleration of 3kg mass is(a) (b) (c) (d)

4. A rope is stretched between two boats at rest oriented towards each other. A sailor in the first boat pulls the rope with a constant force of 100 N. First boat with the sailor has a mass of 250 kg whereas the mass of second boat is double of that mass. If the initial distance between the boats

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 3: LOM Assignment

was 100 m, the time taken for two boats to meet each other is(a) 13.8 s (b) 18.3 s (c) 3.18 s (d) 31.8 s

5. Let be the coefficient of friction between blocks of mass m and M. The pulleys are frictionless and strings are massless. Acceleration of mass m is

(a) (b)

(c) (d)

6. Two blocks and of masses and respectively are connected with the help of a pulley and string as shown. Upper surface of vehicle is smooth but vertical surface is rough.Given a = g/7 and .If B2 is about to slide,coefficient of friction between block and side of vehicle is

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 4: LOM Assignment

(a) 0.4 (b) 0.5 (c) 0.6 (d) 0.3

7. A mass M is hung with a light inextensible string. Tension in horizontal part of string is

(a) mg (b) mg (c) (d)

8. As shown in the fig., if acceleration of M with respect to ground is , then(a) Acceleration of m with respect to M is (b) Acceleration of m with respect to ground is (c) Acceleration of m with respect M is (d) Acceleration of m with respect to ground is

9. A ball is weighing 10 g hits a hard surface vertically with a speed of and rebounds with the same speed. The ball remains in

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 5: LOM Assignment

contact with the surface for 0.01s. The average force exerted by the surface on ball is(a) 100 N (b) 10 N (c) 1 N

(d) 0.1 N

10. Block A of mass m and block B of mass 2m are placed on a fixed triangular wedge by means of massless, inextensible string and a frictionless pulley as shown. The wedge is inclined at to horizontal on both sides. The coefficient of friction between block A and wedge is 2/3 and that between block B and wedge is 1/3. If system of A and B is released from rest then acceleration of A is(a) zero (b) (c) (d)

SECTION-IIThis section contains 7 multiple choice questions. Each question has 4 choices (A), (B), (C) and (D) for its

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 6: LOM Assignment

answer, out which ONE OR MORE is/are correct.

11. In the fig. table is smooth. Then

(a) acceleration of the 3m block (b) the force on the clamp c is mg(c) the force on the clamp by the pulley is

mg(d) the force on the clamp by the pulley is

mg

12. Let F, and f denote the magnitudes of the contact force, normal force and the friction exerted by one surface on the other kept in contact. If none of these is zero.(a) (b) (c) (d)

13. Mark the correct statements about the friction between two bodies

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 7: LOM Assignment

(a) Static friction is always greater than the kinetic friction(b) Coefficient of static friction is always greater than the coefficient of kinematic friction.(c) Limiting friction is always greater than kinetic friction.(d) Limiting friction is never less than static friction

14. Consider a vehicle going on a horizontal road towards east. Neglect any force by the air. The frictional force on the vehicle by the road(a) is towards east if the vehicle is accelerating(b) is zero if the vehicle is moving with a uniform velocity(c) must be towards east(d) must be towards west.

15. Figure shows a heavy block kept on a frictionless surface and being pulled by

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 8: LOM Assignment

two ropes of equal mass m. At t = 0, the force on the left rope is withdrawn but the force on the right end continues to act. Let and be the magnitudes of the force by the right rope and the left rope on the block respectively.(a) (b) (c) (d)

16. For the system shown in figure, the pulleys are light and frictionless. The tension in the string will be

(a) (b) (c) (d)

17. In the arrangement and masses of two blocks A and B, respectively such that . A weightless spring balance S is connected by ideal strings passing over ideal pulleys. The reading of the spring balance (in kg – wt) is

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 9: LOM Assignment

(a) (b) (c) (d)

SECTION-III (Paragraph Type)This section contains 2 groups of questions. Each question has 4 choices (A), (B), (C) and (D) for its answer, out of which ONLY ONE is correct.

An adventurous archeologist crosses between two rock cliffs by slowly going hand – over – hand along a rope stretched between the cliffs. He stops to rest at the middle of the rope as shown in the figure. The rope will break if the tension in it exceeds . The mass of the archaeologist is 90 kg. The rope makes an angle [sin 10 = .1736; cos 10 = .9848 , ]

18. Find the tension in the rope.

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 10: LOM Assignment

(a) 3210 N (b) 2970 N (c) 2867 N(d) 2580 N

19. What should be minimum value of so that rope does not break?

(a) (b) (c) (d)

SECTION-IV (Integer Answer Type)This section contains 2 questions. The answer to each of the questions is a single digit integer, ranging from 0 to 9. The correct digit below the question number in the ORS is be bubbled. (+4, 0)

20. Two blocks one of mass A = 1 kg and B = 2 kg. A force of 5 N is applied on A. Coefficient of friction between A and B is 0.2 and that of between B and horizontal surface is zero. Find the time taken for the front surface of A to coincide with that of B.

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 11: LOM Assignment

21. A parachutist of weight w strikes the ground with his legs fixed and comes to rest with an upward acceleration of magnitude 3g. Force exerted on him by ground during landing iskw. Find k =

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW

Page 12: LOM Assignment

ANDHERI / BORIVALI / DADAR / CHEMBUR / THANE / MULUND/ NERUL / POWAI

TOPIC: LAWS OF MOTION& FRICTION(ANSWER KEY)

1. c 2.d 3.b 4.b 5.c 6.b 7.a

8.a 9.b 10.a 11.a, c 12.a, b, d 13.b, c, d 14.a, b

15.a 16.c 17.c 18.d 19.a20.2 21. 4

Head Office: Andheri: 26245223 MUMBAI / DELHI/ AKOLA / KOLKATA / LUCKNOW