Universe

Q.

What is the dimensional formula of escape velocity?

Q.

What happens to the force between two objects, if the masses of both objects are doubled?

Q.

The force of attraction between two point masses is proportional to the product of their masses and inversely proportional to the distance between them.

1. True
2. False

Q. What fraction of Earth's gravity is the Moon's gravity?

1. One-half
2. Three-fourths
3. One-sixth
4. Two-thirds

Q.

What is gravity?

Q.

State the universal law of gravitation?

Q.

A body falls downwards because of

1. electrical force

2. gravitational force

3. mechanical force

4. magnetic force

Q.

The Law of gravitation gives the gravitational force between:

1. The earth and a point mass only

2. The earth and sun only

3. Any two bodies having some mass

4. two charged bodies only

Q. A ball is thrown vertically upwards which attains a maximum height of $20m$. Calculate the velocity with which the ball is thrown upwards? (Take $g=9.8m{s}^{-2}$)

1. $29.79m{s}^{-1}$
2. $17.79m{s}^{-1}$
3. $19.79m{s}^{-1}$
4. $15.79m{s}^{-1}$

Q. Arrange the following pairs of masses in the decreasing order of the gravitational attraction between them.

1. $CaseIV$: $m_1=2kg$, $m_2=6kg$, $d=2m$
2. $CaseII$: $m_1=2kg$, $m_2=4kg$, $d=2m$
3. $CaseI$: $m_1=1kg$, $m_2=1kg$, $d=1m$
4. $CaseIII$: $m_1=2kg$, $m_2=1kg$, $d=2m$

Q.

What would happen to the Earth, if the Sun suddenly vanishes? (Neglect the gravitational force due to other planets)

1. The Earth will continue to orbit in the same manner.

2. The Earth will move straight along the direction of velocity at that time.

3. The Earth will fall down.

4. The Earth will shatter into pieces.

Q. Two identical copper spheres with uniform density each of radius $R$ are in contact with each other. If the gravitational attraction between them is $F$, then

1. $F\propto R^2$
2. $F\propto R^4$
3. $F\propto \frac{1}{R^2}$
4. $F\propto \frac{1}{R^4}$

Q. A boy is whirling a stone tied with a string in a horizontal circular path. If the string breaks, then the stone ___.

1. will move along a straight line tangential to the circular path
2. will continue to move in the circular path
3. will move along a straight line towards the centre of the circular path
4. will move along a straight line perpendicular to the circular path away from the boy

Q. 1. During a total solar eclipse the moon almost entirely covers thesphere of the sun. Write the relation between the distances andsizes of the sun and moon.2. If the unit of force is 100 N, unit of length is 10 m and unit of time

is 100 s, what is the unit of mass in this system of units?

Q. A string of length $1.5m$ is tied to a stone of mass of $0.2kg$ and is made to revolve at a speed of $1.2m{s}^{-1}$. What is the centripetal force experienced by the stone?

1. $0.173N$
2. $0.192N$
3. $0.160N$
4. $0.123N$

Q.

How many planets are there in our solar system?

1. 10
2. 7
3. 8
4. 9

Q.

The value of gravitational constant, $G$ is

1. $9.8m{s}^{-2}$

2. $6.7N$

3. $6.7\times {10}^{-11}N{m}^{2}k{g}^{-2}$

4. $6.7\times {10}^{-11}N{m}^{2}k{g}^2$