Centripetal Force

Q.

The earth is acted upon by the gravitation of the sun, even though it does not fall into the sun. Why?

Q.

The picture shows a bucket being whirled around in a vertical circle, with the help of a string at a very high but constant speed. What is the correlation between above action and the motion of the moon around the Earth?

1. The bucket is in uniform circular motion like the moon.

2. The force exerted by the thread on the bucket (Tension force) is replaced by the gravitational force in case of the moon.

3. If there is no string, the bucket will not whirl. Similarly, if there is no gravitational force, there will be no moon revolving around the Earth.

4. All of the above.

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

Q. What is responsible for bringing the particles together when a star is first born?

1. Heat energy
2. High temperature
3. Gas pressure
4. Gravitational force

Q. Which of the following is not necessary for keeping a satellite in its orbit ?

1. Centripetal force
2. Frictional force
3. Gravitational force of Earth
4. Tangential speed

Q.

The picture shows a bucket being whirled around in a circle (neglect gravity). Think about the correlation between this action and the motion of the moon around the earth. Then pick out the incorrect statement.

1. The bucket is in uniform circular motion like the moon.

2. The force exerted by the thread on the bucket (Tension force) is replaced by the gravitational force in case of the moon.

3. If there is no string, the bucket will not whirl. Similarly, if there is no gravitational force, there will be no moon revolving around the Earth.

4. All of the above.

Q.

A satellite is revolving around the Earth in a well defined circular orbit. The gravitational force between the Earth and satellite is the centripetal force of the circular motion. What can we say about the motion of the satellite if the gravitational force becomes zero?

1. The satellite will move tangentially.
2. The satellite would come at rest.
3. The satellite will fall towards the center of the Earth.
4. The satellite will continue moving in its circular orbit.

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 fall down.

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

4. The Earth will shatter into pieces.

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.

The value of $\mathrm{g}$ at pole is :

1. greater than the value at the equator

2. less than the value at the equator

3. equal to the value of the equator

4. none of these

Q. A man slides down a light rope the breaking strength of which is $\beta$ times his weight $(\beta <1)$. The maximum acceleration of man so that the rope just breaks is:

1. $(1-\beta )g$
2. $\beta g$
3. $\frac{g}{1+\beta }$
4. $\frac{g}{2-\beta }$

Q. Two satellites orbit the earth in circular orbits, each traveling at a constant speed. The radius of satellite A’s orbit is R, and the radius of satellite B’s orbit is 5R. Both satellites have the same mass. How does F_A, the centripetal force on satellite A, compare with F_B, the centripetal force on satellite B ?

1. F_A = 9F_B
2. F_A = 20F_B
3. F_A = 5F_B
4. F_A = 25F_B

Q. Given the period of an artificial satellite in a circular orbit of radius R is T. Find the period of an artificial satellite having its radius as 4R.

1. 4T
2. 3.6 T
3. 8T
4. 2T

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

Q. The density of core of a planet is P and that of outer shell The radius of core is R and that of planet is same as at the surfacce of core.The ratio.