PHYSICS

1. If energy E, velocity v and time T are taken as fundamental quantities, the dimensional formula for surface tension is

a) [Ev-2T-2] b) [E2vT-2]

c) [Ev-2T-1] d) [E-2v-2-1]

2. A block of mass m is connected to one end of a spring of ‘spring constant’ k. The other end of the spring is fixed to a rigid support. The mass is released slowly so that the total energy of the system is then constituted by only the potential energy, then d is the maximum extension of the spring. Instead, if the mass is released suddenly from the same initial position, the maximum extension of the spring now is ( g= acceleration due to gravity)

a) b) 2d c) d) 4d

3. A particle is projected up from a point at an angle θ, with the horizontal direction. At any time t, if p is the linear momentum, y is the vertical displacement, x is the horizontal displacement, the graph among the following, which does not represent the variation of kinetic energy k of the projectile is

(a) graph (A) (b) graph (B) (c) graph (C) (d) graph (D)

4. A boy of mass 50 kg is standing on a weighing machine placed at the floor of a lift. The machine reads his weight in newtons. What is the reading of the machine, if the lift is moving upwards with a uniform speed of 10 ms-1. ( g = 10 ms-2)

a) 510 N b) 480 N

c) 490 N d) 500 N

5. Six marbles are lined up in a straight groove made on a horizontal frictionless surface as shown below. Two similar marbles in contract, with a common velocity v collide with a row of 6 marbles from left. Which of the following is observed?

a) One marble from the right rolls out with a speed 2v, the remaining marbles do not move.

b) Two marbles from the right roll out with speed v each, the remaining marbles do not move.

c) All six marbles in the row will roll out with a speed v/6 each, the two incident marbles will come to rest.

d) All eight marbles with start moving to the right, each with a speed of v/8