NEET Physics: Questions 852 - 856 of 2142

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Question number: 852

MCQ▾

Question

The mass of a rocket is 600 kg and the relative velocity of the gases ejecting from it is 250 m/s with respect to the rocket. The rate of burning of the fuel in order to give the rocket an initial acceleration 20 m/s 2 in the vertically upward direction (g = 10 m/s 2), will be –

Choices

Choice (4) Response

a.

10 kg/s

b.

60 kg/s

c.

72 kg/s

d.

30 kg/s

Question number: 853

MCQ▾

Question

A tennis ball dropped from a height of 5 m rebounds only 2.5 f meter after hitting the ground. What fraction of energy is lost in the impact?

Choices

Choice (4) Response

a.

1.26

b.

0.466

c.

0.5

d.

2.45

Question number: 854

MCQ▾

Question

A block of mass 5 kg is placed on the floor. The coefficient of static friction is 0.2. A force F of 2.5 N is applied on the block, as shown. Calculate the force of friction between the block and the floor, (g = 9.8 ms -2)

Choices

Choice (4) Response

a.

25 N

b.

7.84 N

c.

2.5 N

d.

zero

Question number: 855

MCQ▾

Question

A bus of mass 2000 kg has an engine which produces a constant power of 50 kW. If the resistance to motion, assumed constant is 2000 N. The maximum speed at which the bus can travel on level road and the acceleration when it is travelling at 15 m/s, will respectively be –

Choices

Choice (4) Response

a.

10 m/s, 5m/s 2

b.

25 m/s, 0.6666 m/s 2

c.

1.0 m/s, 50 m/s 2

d.

50 m/s, 1.0 m/s 2

Question number: 856

MCQ▾

Question

Which of the following statements is false for collisions-

(1) Momentum is conserved in elastic collisions but not in inelastic collisions.

(2) Total-kinetic energy is conserved in elastic collisions but momentum is not conserved.

(3) Total kinetic energy and momentum both are conserved in all types of collisions

(4) Total kinetic energy is not conserved in inelastic collisions but momentum is conserved

Select the correct answers and mark it according to the following codes

Choices

Choice (4) Response

a.

1 and 3 are correct

b.

1 and 2 are correct

c.

1, 2 and 3 are correct

d.

2 and 4 are correct

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