F4 Phys 3.1

All the following will happen to an object placed at P except

• Remain stationary
• Pulled by object at X
• Pulled by object at Y
• Move to X

A rocket travels from P to Q. What is the distance of the rocket from P when the resultant gravitational force on it is zero?

• 0.45x
• 0.50x
• 0.60x
• 0.65x

The gravitational force acting on a satellite on the surface of the earth of radius R is F. What is the gravitational force on the satellite at altitude 2R from the surface of the earth?

• F/2
• F/4
• F/3
• F/9

Why does the Earth stay in orbit around the Sun?

• The gravitational pull of the Sun on the Earth is equal in magnitude but opposite to the gravitational pull of the Earth on the Sun.
• The gravitational pull of the Sun on the Earth acts as the centripetal force.
• The gravitational pull of the Sun on the Earth is negligible
• The gravitational pull on the Earth by the Sun is balanced by the centripetal force on the Earth.

Which of the following is true about the gravitational force?

• Gravitational force of a planet on an object is directly proportional to mass of the planet only.
• The effect of distance between two objects is less than the effect of mass on gravity.
• Gravitational force is inversely proportional to distance between two objects.
• Gravitational force is inversely proportional to the square of the distance between two objects.

Gravitational acceleration at the earth’s surface is g. Suppose the Earth were compressed to half its diameter. The new acceleration due to the gravitiy at its surface is

• 2g
• 4g
• g/2
• g/4

Which of the following is true about the gravitational acceleration outside the surface of the earth?

• Uniform for all points outside the earth’s surface.
• Directly proportional to the distance from the centre of the earth.
• Inversely proportional to the distance from the centre of the earth.
• Inversely proportional to the square of the distance from the centre of the earth

An object of mass 1 kg weighs 10 N on the surface of the earth of radius, r. If the the object is placed at a height, r from the earth’s surface,

• its weight is 5 N.
• its mass is 0.5 kg.
• its weight is 2.5 N.
• its mass is 0.25 kg.

Weight of a boy on the earth’s surface in equator region is 500 N. Due to rotation of earth, his weight

• will be greater than 500 N at the two poles.
• will be less than 500 N at the two poles.
• will remain the same on any place on the earth’s surface

Which of the following is not true about centripetal force?

• Always acting perpendicular to the direction of displacement
• One of the examples is gravitational force attracts the Moon to the Earth.
• Always acting towards the centre of the circle.
• As the speed of rotation decreases, the centripetal force increases.