Gravitations, Solids & Fluids

A body of mass 60 g experiences a gravitational force of 3.0 N, when placed at a particular point. The magnitude of the gravitational field intensity at that point is

• 0.05 N/kg

• 50 N/kg

• 20N/kg

• 180N/kg

The escape velocity from the Earth's surface is v. The escape velocity from the surface of another planet having a radius, four times that of Earth and same mass density is :

• 4v

• v

• 2v

• 3v

A body weighs 72 N on the surface of the earth. What is the gravitational force on it, at a height equal to half the radius of the earth?

• 32N

• 30N

• 24N

• 48N

Two astronauts are floating in gravitational free space after having lost contact with their spaceship. The two will

• Move towards each other

• Move away from each other

• will become stationary

• keep floating at same distance between them

The terminal velocity of a copper ball of radius 5 mm falling through a tank of oil at room temperature is 10 cm s⁻¹. If the viscosity of oil at room temperature is 0.9 kg m⁻¹ s⁻¹, the viscous drag force is :

• 4.23* 10^-6N

• 8.48* 10^-3N

• 8.48* 10^-5N

• 4.23* 10^-3N

If a soap bubble expands, the pressure inside the bubble

• Decreases

• Increases

• Remains the same

• Is equal to the atmospheric pressure

A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of the water in the capillary is 5 g. Another capillary tube of radius 2r is immersed in Water. The mass of water that will rise in this tube is :

• 5g

• 10g

• 20g

• 2.5g

A wire of length L, are of cross section A is hanging from a fixed support. The length of the wire changed to L₁ when mass M is suspended from its free end. The expression for Young's modulus is :

• Mg(L₁-L)/AL

• MgL/AL₁

• MgL/A(L₁-L)

• MgL₁/AL

A small sphere of radius ‘r’ falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to

• r³

• r²

• r⁵

• r⁴

The bulk modulus of a spherical object is 'B'. If it is subjected to uniform pressure 'P', the fractional decrease in radius is

• B/3p

• 3p/B

• p/3B

• p/B