31.

Consider a car moving on a straight road with a speed of 100 m/s. The distance at which car can be stopped is [µ =k 0.5]

• 800 m

• 1000 m

• 600 m

• 600 m

A ball is released from the top of a tower of height h metres. It takes T seconds to reach the ground. What is the position of the ball in T/3 seconds?

• h/9 metres from the ground

• 7h/9 metres from the ground

• 8h/9 metres from the ground

• 8h/9 metres from the ground

An automobile travelling with speed of 60 km/h, can brake to stop within a distance of 20 cm. If the car is going twice as fast, i.e 120 km/h, the stopping distance will be

• 20 m

• 40 m

• 60 m

• 60 m

A machine gun fires a bullet of mass 40 g with a velocity 1200 ms⁻¹. The man holding it can exert a maximum force of 144 N on the gun. How many bullets can he fire per second at the most?

• one 

• Four

• Two

• Two

Two masses m₁ = 5 kg and m₂ = 4.8 kg tied to a string are hanging over a light frictionless pulley. What is the acceleration of the masses when lift free to move?
(g = 9.8 m/s² )

• 0.2 m/s²

• 9.8 m/s²

• 5 m/s²

• 5 m/s²

A block rests on a rough inclined plane making an angle of 30° with the horizontal. The coefficient of static friction between the block and the plane is 0.8. If the frictional force on the block is 10 N, the mass of the block (in kg) is (take g = 10 m/s² )

• 2.0

• 4.0

• 1.6 

• 1.6 

It is found that if a neutron suffers an elastic collinear collision with deuterium at rest, fractional loss of its energy is p_d; while for its similar collision with carbon nucleus at rest, fractional loss of energy is p_c. The values of p_d and p_c are respectively :

• (0,1)

• (.89,.28)

• (.28,.89)

• (0,0)

The one which does not represent a force in any context is

• Friction

• Impulse

• Tension 

• Weight

Water from a hose pipe of radius 5 cm strikes a wall normally at a speed of 5 ms^-1. The force exerted on the wall in newton is

• $13.5 \mathrm{\pi }$

• $6.25 \mathrm{\pi }$

• $62.5\mathrm{\pi }$

• $27\mathrm{\pi }$

A stone of density 2000 kg m^-3 completely immersed in a lake is allowed to sink from rest. If the effect of friction is neglected, then after 4 seconds, the stone will reach a depth of

• 78.4 m

• 39.2 m

• 19.6 m

• 9.8 m