﻿ The velocity with which a projectile must be fired so that it esc

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# 1.The velocity with which a projectile must be fired so that it escapes earth's gravitation does not depend onmass of the earth mass of the projectile radius of the projectile's orbit gravitational constant

B.

mass of the projectile

For projectile to leave the gravitational field of the earth, its kinetic energy would be at least equal to its potential energy.

That is

⇒          ve =  $\sqrt{\frac{2\mathrm{GM}}{\mathrm{R}}}$

Where G is the universal gravitational constant

M is the mass of the earth

R is the radius of the earth

Hence the escape velocity of a projectile is independent of its own mass.

2.

The motion of planets in the solar system is an example of the conservation of

• mass

• linear momentum

• angular momentum

• energy

3.

A body starting from rest moves along a straight line with a constant acceleration. The variation of speed (v) with distance ( s ) is represented by the graph

4.

A lead shot of  1 mm diameter falls through a long column of glycerine. The variation of its velocity  'v'  with distance covered is represented by

5.

Assertion: The earth is slowing down and as a result the moon is coming nearer to it.

Reason: The angular momentum of the earth moon system is not conserved.

• if both assertion and reason are true and the reason is the correct explanation of the assertion

• if both assertion and reason are true and the reason is not the correct explanation of the assertion

• if assertion is true but reason is false

• if both assertion and reason are false statements

6.

Assertion:  The Coulomb force is dominating force in the universe.

Reason: The Coulomb force is weaker than the gravitational force.

• if both assertion and reason are true and the reason is the correct explanation of the assertion

• if both assertion and reason are true and the reason is not the correct explanation of the assertion

• if assertion is true but reason is false

• if both assertion and reason are false statements

7.

Assertion: The length of the day is slowly increasing.

Reason: The dominant effect causing a slowdown in the rotation of the earth is the gravitational pull of other planets in the solar system.

• if both assertion and reason are true and the reason is the correct explanation of assertion

• if both assertion and reason are true and the reason is not the correct explanation of the assertion

• if assertion is true but reason is false

• if both assertion and reason are false statements

8.

A ball is thrown vertically upwards. Which of the following  plots represents the speed-time graph of the ball during its flight if the air resistance is not ignored?

9.

An earthquake generates both transverse (S) and longitudinal (P) sound waves in the earth. The speed of S waves is about 4.5 km/s and that of P waves is about 8.0 km/s. A seismograph records P and S waves from an earthquake. The first P wave arrives 4.0 min before the first S wave. The epicentre of the earthquake is located at a distance about

• 25 km

• 250 km

• 2500 km

• 5000 km

10.

Bernoulli's equation is a consequence of conservation of

• energy

• linear momentum

• angular momentum

• mass