A shell is fired from a canon, it explodes in mid air, its total

(A)

momentum increases

(B)

momentum decreases

(C)

kinetic energy increases

(D)

kinetic energy decreases

Question-2

If the force on a rocket moving with a velocity of 300 m/s is 345 N, then the rate of combustion of the fuel ,is

(A)

0.55 kg/s

(B)

0.75 kg/s

(C)

1.15 kg/s

(D)

2.25 kg/s

Question-3

A block of mass 50 kg is placed on a rough inclined plane.The inclination is gradually increased to 30° when the block starts sliding down.Find the magnitude of the limiting friction.

(A)

375 N

(B)

245 N

(C)

275 N

(D)

200 N

Question-4

A disc revolves in a horizontal plane at a sready rate of 3 r.p.s.A coin will remain on the disc if it is kept at a distance of 2 cm from the axis of rotation.What is the coeffecient of friction between the coin and the disc? g = 9.8 m/s^{2}

(A)

0.724

(B)

0.856

(C)

0.987

(D)

0.685

Question-5

Two iron blocks of equal mass but with double surface area slide down an inclined plane with friction coefficient μ.If the first block with surface area A experience a frictional force f, then the second block with surface area 2A will experience a frictional force

(A)

f/2

(B)

f

(C)

2f

(D)

4f

Question-6

Two blocks P and Q are released at the top of a rough inclined plane so that P slides along the plane and Q falls down freely. Which will have higher velocity on reaching the ground?

(A)

P

(B)

Q

(C)

Both will reach the ground with same velocity

(D)

It depends on the coefficient of friction

Question-7

A block of metal of mass 2 kg is resting on a frictionless floor.It is struck by a jet releasing water at the rate of 1 kg/sec and at a speed of 5 m/s.What will be the initial acceleration of the block ?

(A)

3.5 m/s^{2}

(B)

4.5 m/s^{2}

(C)

2.5 m/s^{2}

(D)

none of these

Question-8

A 10 kg stone is suspended with a rope of breaking stength 30 kg wt.The minimum time in which the stone can be raised through a height 10 m starting from rest is (taking g = 10 N/kg):

(A)

0.5 seconds

(B)

1.0 seconds

(C)

√2 / √3 seconds

(D)

2.0 seconds

Question-9

An air craft executes a horizontal loop at a speed of 720 km/h with its wings banked at 15° .What is the radius of the loop?

(A)

13 x 10^{3} m

(B)

15.2 x 10^{3} m

(C)

13.6 x 10^{3} m

(D)

None of these

Question-10

A heavy uniform chain lies on horizontal table top.If the coeffecient of friction between the chain and the table surface is 0.25,then the maximum friction of the length of the chain that can hang over one edge of the table is

(A)

20 %

(B)

25 %

(C)

35 %

(D)

15 %

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