GRAVITATION

Multiple Choice

Name the force that causes acceleration of an object moving along a circle and keeps the body moving.

• centripetal force

• centrifugal force

• repulsive force

• attractive force

Multiple Choice

For a given force acceleration is inversely proportional to the mass of an object.

A. The above statement is correct because F=ma

B.The statement is not correct because the value of g is constant.

• option A is wrong

• both option A and B are wrong because the reasons given are wrong

• only option A is correct

• both A and B are correct.

Multiple Choice

Which of the following Laws of Kepler did Newton use to calculate the force of attraction?

• Sun is situated at the centre of the orbit

• The orbit of the planet is ellipse

• The cube pf the mean distance of a planet from the sun is proportional to the square of its orbital period.

• The line joining the planet and the sun sweeps equal areas in equal interval of time.

Multiple Choice

The SI unit of G

• Ncm²/kg²

• Nm²kg²

• Nm²/kg²

• Nkg/m²

Multiple Choice

The SI unit of weight

• kg

• N/m²

• N

• N cm/s²

Multiple Choice

What is the gravitational force between two objects?

• attraction at large distance only

• attraction at small distance only

• attraction at all distances

• attraction at large distances but repulsive at small distances

Multiple Choice

A ball is thrown up, the value of g will be?

• zero

• negative

• positive

• negligible

Multiple Choice

The gravitational forces cause

• Tides

• Motion of moon

• none of these

• both a and b

Multiple Choice

The earth attracts the moon with a gravitational force of 10²² N.The moon attracts the earth with a gravitational force of

• less than 10²² N

• 10²² N

• Greater than 10²² N

• 10-²² N

Multiple Choice

The upward force exerted by water on an object in it is called

• pressure

• thrust

• buoyancy

• drag

Multiple Choice

The relative density of an object is determined comparing its density with that of

• water

• air

• iron

• wood

Multiple Choice

A stone is released from the top of the tower with height 81.64 m.Calculate its final velocity before touching the ground.

• 90m/s

• 60m/s

• 40m/s

• 50m/s

Multiple Choice

A ball thrown up vertically return to the earth after 12s . Find the velocity with which it was thrown up?

• 29.4m/s

• 58.8 m/s

• 36.5m/s

• 48.8m/s

Multiple Choice

The volumes of 180g and 18g of a substance is 200cm³ and 20cm³ respectively.If the density of water is 1g/cm³ then

• both will sink

• both will float

• first substance will float and the second will sink

• the second will float and the first will sink

Multiple Choice

According to Archimedes principle the upward force experiencing on a body immersed in it will be equal to

• the amount of water displaced

• the volume of water displaced

• the weight of the water displaced

• the area of the object in contact with the water