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11.

A and B are two wires. The radius of A is twice that of B. They are stretched by the same load. Then the stress on B is

A) equal to that on A

B) four times that on A

C) two times that on A

D) half that on A

12.

A block of mass 5 kg resting on a horizontal surface is connected by a cord, passing over a light frictionless pulley to a hanging block of mass 5 kg. The coefficient of kinetic friction between the block and the surface is 0.5. Tension in the cord is : (g = 9.8 m/sec2)

A) 49 N

B) Zero

C) 36.75 N

D) 2.45 N

13.

A solid cylinder of mass m and radius R rolls down the inclined plane without slipping. The speed of its C.M. when it reaches the bottom is

A) $\sqrt{2gh}$

B) $\sqrt{\frac{4gh}{3}}$

C) $\sqrt{\frac{3}{4gh}}$

D) $\sqrt{4gh}$

14.

Escape velocity when a body of mass m is thrown vertically from the surface of the earth is v, what will be the escape velocity of another body of mass 4 m is thrown vertically

A) v

B) 2v

C) 4v

D) None of these

15.

A man holding a rifle (mass of person and rifle together is 100kg) stands on a smooth surface and fires 10 shots horizontally in 5 sec. Each bullet has a mass of 10 g with a muzzle velocity of 800 ms-1 . The velocity which the rifleman attains after firing 10 shots will be

A) 8 m/s

B) 0.8m/s

C) 0.08 m/s

D) -0.8m/s

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