May, 2022Flame Institute

Assertion : When a gas is allowed to expand, work done by gas is positive. Reason : Force due to gaseous pressure and displacement (of piston) are in the same direction.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not the correct explanation of the assertion. (c) If assertion is …

15. A pulley fixed to the ceilling carries a string with blocks of mass m and 3 m attached to its ends. The masses of string and pulley are negligible. When the system is released, its centre of mass moves with what acceleration

(a) 0 (b) g/4 (c) g/2 (d) -g/2 Ans. b (9)

3. Assertion : Work done by friction on a body sliding down an inclined plane is positive. Reason : Work done is greater than zero, if angle between force and displacement is acute or both are in same direction.

Assertion : A person working on a horizontal road with a load on his head does no work. Reason : No work is said to be done, if directions of force and displacement of load are perpendicular to each other.

11. The vector sum of two forces is perpendicular to their vector differences. In that case, the force

(a) Are equal to each other in magnitude (b) Are not equal to each other in magnitude (c) Cannot be predicted (d) Are equal to each other Ans. a (8)

10. A false balance has equal arms. An object weigh X when placed in one pan and Y when placed in other pan, then the weight W of the object is equal to

(a) √X Y (b) X + Y / 2 (c) X2 + Y2 / 2 (d) 2 / √X2 + Y2 / 2 Ans. b (10)

5. Three weights W, 2W and 3W are connected to identical springs suspended from a rigid horizontal rod. The assembly of the rod and the weights fall freely. The positions of the weights from the rod are such that

(a) 3W will be farthest (b) W will be farthest (c) All will be at the same distance (d) 2W will be farthest Ans. c (4)

A ship of mass 3 x 10 ^7 kg initially at rest is pulled by a force of 5 x 10 ^ 4 N through a distance of 3 m. Assume that the resistance due to water is negligible, the speed of the ship is

(a) 1.5 m/s (b) 60 m/s (c) 0.1 m/s (d) 5 m/s Ans. c (6)

2. A closed compartment containing gas is moving with some acceleration in horizontal direction. Neglect effect of gravity. Then the pressure in the compartment is

(a) Same everywhere (b) Lower in front side (c) Lower in rear side (d) Lower in upper side Ans. b (9)

A body moves from rest with a constant acceleration. Which one of the following graphs represents the variation of its kinetic energy K with the distance travelled x ?

Answer: c (14)

The graph between E and v is

Answer: a (9)

When forces F1 , F2 , F3 , are acting on a particle of mass m such that F2 and F4 are mutually perpendicular, then the particle remains stationary. If the force F1 is now removed then the acceleration of the particle is

(a) F 1 / m (b) F2 F3 / m F1 (c) (F2 – F3 ) / m …

A particle is placed at the origin and a force is acting F=kx on it (where k is positive constant). If U(0)=0, the graph of U(x) versus x will be (where U is the potential energy function)

Answer: a (6)

4. The mass of a body measured by a physical balance in a lift at rest is found to be m. If the lift is going up with an acceleration a, its mass will be measured as

(a) m (1- a/g) (b) m (1 + a/g) (c) m (d) Zero Ans. c (5)

The relationship between the force F and position x of a body is as shown in figure. The work done in displacing the body from x = 1 m to x = 5 m will be

(a) 30 J (b) 15 J (c) 25 J (d) 20 J Answer: b (4)

The diagrams represent the potential energy U of a function of the inter-atomic distance r. Which diagram corresponds to stable molecules found in nature.

Answer: a (13)

A particle of mass m moving with a velocity u makes an elastic one dimensional collision with a stationary particle of mass m establishing a contact with it for extremely small time T. Their force of contact increases from zero to F0 linearly in time T/4, remains constant for a further T/2 time and decreases linearly from F0 to zero in further time T/4 as shown. The magnitude possessed by F0 is

(a) mu/T (b) 2mu/T (c) 4mu/3T (d) 3mu/4T Answer: c (8)

23. Two masses m1 and m2 (m1 > m2) are connected by massless flexible and inextensible string passed over massless and frictionless pulley. The acceleration of centre of mass is

(a) (m1 – m2 / m1 + m2 ) 2 g (b) m1 – m2 / m1 + m2 g (c) m1 + m2 / m1 – m2 g (d) Zero Ans . a (24)

19. A light string passing over a smooth light pulley connects two blocks of masses m 1 and m 2 (vertically). If the acceleration of the system is g/8 then the ratio of the masses is

(a) 8 : 1 (b) 9 : 7 (c) 4 : 3 (d) 5 : 3 Ans. b (8)

10. A block of mass m1 rests on a horizontal table. A string tied to the block is passed on a frictionless pulley fixed at the end of the table and to the other end of string is hung another block of mass m 2 . The acceleration of the system is on a frictionless pulley fixed at the end of the table and to the other end of string is hung another block of mass . The acceleration of the system is

(a) m 2 g / (m1 + m 2 ) (b) m1 g / (m1 + m 2 ) (c) g (d) m 2 g / m1 Ans. a (47)

11. A 2 kg block is lying on a smooth table which is connected by a body of mass 1 kg by a string which passes through a pulley. The 1 kg mass is hanging vertically. The acceleration of block and tension in the string will be

(a) 3.27 m/s ^ 2 , 6.54 N (b) 4.38,m/s ^ 2 , 6.54 N (c) 3.27 m/s ^ 2 , 9.86 N (d) 4.38,m/s ^ 2 , 9.86 N Ans. a (25)

The force required to stretch a spring varies with the distance as shown in the figure. If the experiment is performed with the above spring of half length, the line OA will

(a) Shift towards F-axis (b) Shift towards X-axis (c) Remain as it is (d) Become double in length Answer: a (12)

Figure shows the F-x Where F is the force applied and x is the distance covered by the body along a straight line path. Given that F is in newton and x in metre, what is the work done ?

(a) 10 J (b) 20 J (c) 30 J (d) 40 J Answer: a (18)

The potential energy of a particle varies with distance x as shown in the graph.

The force acting on the particle is zero at (a) C (b) B (c) B and C (d) A and D Answer: c (28)

The force acting on a body moving along x-axis varies with the position of the particle as shown in the fig.

The body is in stable equilibrium at (a) x=x1 (b) x=x2 (c) both x1 and x2 (d) neither x1 nor x2 Answer: b (11)

Which of the following graphs is correct between kinetic energy (E), potential energy (U) and height (h) from the ground of the particle

Answer: A (8)

7. Two bodies of mass 3 kg and 4 kg are suspended at the ends of massless string passing over a frictionless pulley. The acceleration of the system is (g = 9.8 m/s ^ 2

(a) 4.9 m/s 2 (b) 2.45 m/s 2 (c) 1.4 m/s 2 (d) …

A particle, initially at rest on a frictionless horizontal surface, is acted upon by a horizontal force which is constant in size and direction. A graph is plotted between the work done (W) on the particle, against the speed of the particle, (v). If there are no other horizontal forces acting on the particle the graph would look like

Answer: d (55)

5. Two masses 2 kg and 3 kg are attached to the end of the string passed over a pulley fixed at the top. The tension and acceleration are

(a) 7g/8 , g/8 (b) 21g/8 , g/8 (c) 21g/8, g/5 (d) 12g/5, g/5 Ans. d (7)

The potential energy of a system is represented in the first figure. the force acting on the system will be represented by

Answer: c (6)

A force F acting on an object varies with distance x as shown here. The force is in newton and x in metre. The work done by the force in moving the object from x=0 to x=6m is

(a) 4.5 J (b) 13.5 J (c) 9.0 J (d) 18.0 J Answer: b (8)

2. A rope of length L is pulled by a constant force F. What is the tension in the rope at a distance x from the end where the force is applied

(a) FL/x (b) F(L-x)/L (c) FL/L-x (d) Fx/L-x Ans. b (5)

The adjoining diagram shows the velocity versus time plot for a particle. The work done by the force on the particle is positive from

(a) A to B (b) B to C (c) C to D (d) D to E Answer: a (8)

A particle is dropped from a height h . A constant horizontal velocity is given to the particle. Taking g to be constant every where, kinetic energy E of the particle w. r. t. time t is correctly shown in

Answer: a (31)

The relation between the displacement X of an object produced by the application of the variable force F is represented by a graph shown in the figure. If the object undergoes a displacement from X=0.5 m to X=2.5 m the work done will be approximately equal to

(a) 16 J (b) 32 J (c) 1.6 J (d) 8 J Answer: a (25)

13. Which of the following groups of forces could be in equibrium

(a) 3 N, 4 N, 5 N (b) 4N, 5 N, 10 N (c) 30N, 40 N, 80 N (d) 1N, 3 N, 5 N Ans. a (8)

A particle of mass 0.1 kg is subjected to a force which varies with distance as shown in fig. If it starts its journey from rest at x=0, its velocity at x=12m is

(a) 0 m/s (b) 20 √2 m/s (c) 20 √3 m/s (d) 40 m/s Answer:d (7)

Month: May 2022

Login with your site account

Register a new account