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23. A bullet of mass 0.1 kg is fired with a speed of 100 m/sec, the mass of gun is 50 kg. The velocity of recoil is

(a) 0.2 m/sec (b) 0.1 m/sec (c) 0.5 m/sec (d) 0.05 m/sec Ans. a (11)

A bullet is fired from a gun. The force on the bullet is given by f = 600- 2 x 10 5 t where F is in newtons and t in seconds. The force on the bullet becomes zero as soon as it leaves the barrel. What is the average impulse imparted to the bullet

(a) 9 Ns (b) Zero (c) 0.9 Ns (d) 1.8 Ns ans. c (23)

21. A body of mass 0.25 kg is projected with muzzle velocity 100ms ^-1 from a tank of mass 100 kg. What is the recoil velocity of the tank

(a) 5 ms -1 (b) 25ms -1 (c) 0.5 ms -1 (d) 0.25 ms -1 ans. …

A set of n identical cubical blocks lies at rest parallel to each other along a line on a smooth horizontal surface. The separation between the near surfaces of any two adjacent blocks is L. The block at one end is given a speed v towards the next one at time t=0 . All collisions are completely inelastic, then

(a) The last block starts moving at t=(n-1)L/v (b) The last block starts moving at t=n(n-1)L/2v (c) The centre of mass of the system will have a final speed v (d) The centre of mass of the system will have …

A particle P moving with speed v undergoes a head -on elastic collision with another particle Q of identical mass but at rest. After the collision

(a) Both P and Q move forward with speed v/2 (b) Both P and Q move forward with speed v/√2 (c) P comes to rest and Q moves forward with speed v (d) P and Q move in opposite directions …

A body of mass m moving with velocity v collides head on with another body of mass 2m which is initially at rest. The ratio of K.E. of colliding body before and after collision will be

(a) 1 : 1 (b) 2 : 1 (c) 4 : 1 (d) 9 : 1 Answer: d (6)

Consider elastic collision of a particle of mass m moving with a velocity u with another particle of the same mass at rest. After the collision the projectile and the struck particle move in directions making angles θ1 and θ2 respectively with the initial direction of motion. The sum of the angles θ1+θ2, is

(a) 45° (b) 90° (c) 135° (d) 180° Answer:b (8)

Two particles of masses m1 and m2 in projectile motion have velocities

(a) Zero (b) (m1+m2)gt0 (c) 2(m1+m2)gt0 (d) 1/2(m1+m2)gt0 Answer: c (12)

15. A vessel at rest explodes into three pieces. Two pieces having equal masses fly off perpendicular to one another with the same velocity 30 meter per second. The third piece has three times mass of each of other piece. The magnitude and direction of the velocity of the third piece will be

(a) 10√2 m/second and 135° from either (b) 10√2 m/second and 45° from either (c) 10/√2 m/second and 135° from either (d) 10/√2 m/second and 45° from either Answer: a (3)

A shell is fired from a cannon with velocity v m/sec at an angle θ with the horizontal direction. At the highest point in its path it explodes into two pieces of equal mass. One of the pieces retraces its path to the cannon and the speed in m/sec of the other piece immediately after the explosion is

(a) 3v cosθ (b) 2v cosθ (c) 3/2v cosθ (d) √3/2 cosθ Answer: a (7)

A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to

(a) t1/2 (b) t3/4 (c) t3/2 (d) t2 Answer: …

Consider the following two statements 1. Linear momentum of a system of particles is zero 2. Kinetic energy of a system of particles is zero Then

(a) 1 implies 2 and 2 implies 1 (b) 1 does not imply 2 and 2 does not imply 1 (c) 1 implies 2 but 2 does not imply 1 (d) 1 does not imply 2 but 2 implies 1 …

An open knife edge of mass ‘m’ is dropped from a height ‘h’ on a wooden floor. If the blade penetrates upto the depth ‘d’ into the wood, the average resistance offered by the wood to the knife edge is

(a) mg (b) mg (1-h/d) (c) mg (1+h/d) (d) mg(1+h/d)2 Answer: c (5)

The kinetic energy acquired by a mass m in travelling a certain distance d starting from rest under the action of a constant force is directly proportional to

(a) √m (b) Independent of m (c) 1/√m (d) m …

A particle free to move along the x-axis has potential energy given by U(x) = K [1-exp(-x)2] for – ∞<–x<–+∞, where k is a positive constant of appropriate dimensions. Then

(a) At point away from the origin, the particle is in unstable equilibrium (b) For any finite non-zero value of x, there is a force directed away from the origin (c) If its total mechanical energy is k/2, it has …

A ball hits the floor and rebounds after inelastic collision. In this case

(a) The momentum of the ball just after the collision is the same as that just before the collision (b) The mechanical energy of the ball remains the same in the collision (c) The total momentum of the ball and …

A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, the work required to pull the hanging part on to the table is

(a) MgL (b) MgL/3 (c) MgL/9 (d) MgL/18 Answer: D (6)

If W1, W2 ,and W3 represent the work done in moving a particle from A to B along three different paths 1, 2 and 3 respectively (as shown) in the gravitational field of a point mass m, find the correct relation between W1, W2 and W

(a) W1>W2>W3 (b) W1=W2=W3 (c) W1<W2<W3 (d) W2 >W1>W3 Answer: b (8)

A particle of mass m is moving in a horizontal circle of radius r under a centripetal force equal to -K/r2 , where K is a constant. The total energy of the particle is

a) K/2r (b) – (K/2r) (c) -(K/r) (d) K/r Answer: b (39)

7. A 100 g iron ball having velocity 10 m/s collides with a wall at an angle 30° and rebounds with the same angle. If the period of contact between the ball and wall is 0.1 second, then the force experienced by the wall is

(a) 10 N (b) 100 N (c) 1.0 N (d) 0.1 N answer : a (6)

The displacement x of a particle moving in one dimension under the action of a constant force is related to the time t by the equation t=√x+3 , where x is in meters and t is in seconds. The work done by the force in the first 6 seconds is

(a) 9 J (b) 6 J (c) 0 J (d) 3 J Answer: C (5)

6. If a force of 250 N act on body, the momentum acquired is 125 kg-m/s. What is the period for which force acts on the body

(a) 0.5 sec (b) 0.2 sec (c) 0.4 sec (d) 0.25 sec answer : a (29)

5. A wagon weighing 1000 kg is moving with a velocity 50km/h on smooth horizontal rails. A mass of 250 kg is dropped into it. The velocity with which it moves now is

(a) 2.5 km/hour (b) 20 km/hour (c) 40 km/hour (d) 50 km/hour answer : c (4)

A force F = -K(yi+xj) (where K is a positive constant) acts on a particle moving in the xy-plane. Starting from the origin, the particle is taken along the positive x-axis to the point (a, 0) and then parallel to the y-axis to the point (a, a). The total work done by the force F on the particles is

(a) -2 Ka2 (b) 2 Ka2 (c) – Ka2 (d) Ka2 Answer: …

4. In which of the following cases forces may not be required to keep the

(a) Particle going in a circle (b) Particle going along a straight line (c) The momentum of the particle constant (d) Acceleration of the particle constant ANSWER: c (9)

3. A rocket has a mass of 100 kg. 90% of this is fuel. It ejects fuel vapours at the rate of 1 kg/sec with a velocity of 500 m/sec relative to the rocket. It is supposed that the rocket is outside the gravitational field. The initial upthrust on the rocket when it just starts moving upwards is

(a) Zero (b) 500 N (c) 1000 N (d) 2000 N ANSWER : b (10)

A lorry and a car moving with the same K.E. are brought to rest by applying the same retarding force, then

(a) Lorry will come to rest in a shorter distance (b) Car will come to rest in a shorter distance (c) Both come to rest in a same distance (d) None of the above Answer: C (6)

2. A player caught a cricket ball of mass 150 gm moving at a rate of 20 m/s. If the catching process be completed in 0.1 s, then the force of the blow exerted by the ball on the hands of the player is

(a) 0.3 N (b) 30 N (c) 300 N (d) 3000 N ANSWER : b (6)

1. A jet plane flies in the air because

(a) The gravity does not act on bodies moving with high speeds (b) The thrust of the jet compensates for the force of gravity (c) The flow of air around the wings causes an upward force, which …

If g is the acceleration due to gravity on the earth’s surface, the gain in the potential energy of an object of mass m raised from the surface of earth to a height equal to the radius of the earth R, is

(a) 1/2 mgR (b) 2 mgR (c) mgR (d) 1/4 mgR Answer: A (5)

58. The main difference between the molecules of chlorophyll a and b is

(16)

6. The researches on photosynthesis started

(a) In the 17th century (b) In the 18th century (c) In the 19th century (d) In the early 20th century Answer: (b) In the 18th century Explanation: (b) (15)

58. Absorption of water by gram is the process of

(a) Diffusion (b) Imbibition (c) Endosmosis (d) Exosmosis (e) All of the above Ans.(b) In gram and wheat the volume increase by adsorption of water, in plant systems, adsorption of water takes place by cell wall. (35)

57. In the process of osmosis

(a) Both protoplasm and cell wall act as a single layer (b) Only protoplast acts as a single layer (c) Only cell membrane acts as a single layer (d) None of the above Ans. c (14)

56. In seed germination, the first phenomenon takes place is

(a) Diffusion (b) Osmosis (c) Imbibition (d) All the above Ans. (c) Imbibition takes place by outermost layer of seed. (16)

60. Osmosis involves

(a) Cell to cell movement of water (b) Movement of water through cortical cells (c) Active absorption of water through roots (d) All the above Ans. d (12)

59. Osmosis is the property of

(a) Solutes (b) Solutions (c) Semipermeable membrane (d) Solvent Ans. (c) It is essential for operation of osmosis. In plant–water relations, biomembranes largely function as semipermeable membranes. (54)

8. ‘Photosynthesis is the conversion of light energy within a plant’ was first stated by

(a) Willstatter and Stoll (b) Mayor and Anderson (c) Benson and Calvin (d) Robert Mayer Answer: (d) Robert Mayer Explanation: (d) Robert Mayer (1845) proposed that light has radiant …

7. Most of the plants contain a green colouring pigment which is responsible for photosynthesis. This pigment was named chlorophyll by

(a) Melvin Calvin (b) Jean Senebie (c) Julius Robert Mayer (d) Pelletier Caventou Answer: (d) Pelletier Caventou Explanation: (d) Pelletier and Caventou (1818) discovered chlorophyll. It could be separated from leaf by boiling in alcohol (12)

51. In the course of imbibition, the volume of the system

(a) Decreases (b) Increases (c) Unchanged (d) None of these Ans. (b) In the course of imbibition the volume of the system increases i.e., swelling occurs. The total volume of the water imbibed plus the imbibing material is less after imbibition …

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