Centripetal Force

Q. What is the angle between velocity and acceleration of a body moving in a uniform circular motion?

1. $0^{\circ }$
2. ${90}^{\circ }$
3. ${80}^{\circ }$
4. ${45}^{\circ }$

Q.

A particle is moving with uniform speed along the circumference of a circle of radius $R$ under the action of a central fictitious force $F$ which is inversely proportional to $R^3$. Its time period of revolution will be given by:

1. $T\propto R^{5/2}$

2. $T\propto R^2$

3. $T\propto R^{4/3}$

4. $T\propto R^{3/2}$

Q.

The centripetal force on a satellite revolving around the Earth is $F$. The gravitational force of the Earth is also $F$. What will be the net force on satellite?

Q. Centripetal force is the force directed towards the centre of curvature of the path.

1. True
2. False

Q.

Imagine a light planet revolving around a very massive star in a circular orbit of the radius $R$ with a period of revolution $T$. If the gravitational force of attraction between the planet and the star is proportional to $R^{\raisebox{1ex}{$-5$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$, then

1. $T^2$ is proportional to $R^3$

2. $T^2$ is proportional to $R^{7/2}$

3. $T^2$ is proportional to $R^{3/2}$

4. $T^2$ is proportional to $R^{3/73}$

Q. The Martians use force (F) , acceleration (A) and time (T) as their fundamental physical quantities. The dimensions of length on Martians' system are:

1. FT²
2. F^-1 A² T^-1
3. F^-1 A^o T^-1
4. AT²

Q.

Why is centripetal force equal to weight?

Q. Why satellites, which are revolving around the earth, do not fall into the earth?

Q.

A thin circular ring of mass $M$ and radius $r$ is rotating about its axis with an angular speed $\omega$. Two particles having mass $m$ each are now attached at diametrically opposite points. The angular speed of the ring will become:

1. $\begin{array}{l}\omega \left(\frac{M}{M+2m}\right)\end{array}$

2. $\begin{array}{l}\omega \left(\frac{M}{M+m}\right)\end{array}$

3. $\begin{array}{l}\omega \left(\frac{M+2m}{M}\right)\end{array}$

4. $\begin{array}{l}\omega \left(\frac{M-2m}{M+2m}\right)\end{array}$

Q. ntIf a planet of a given density were made larger, its force of attraction for an object on its surface would increase because of the planets greater mass but would decrease because of the greater distance from the object to the centre of the planet. Which effect predominates?n

Q.

Merry go round uses the theory of___

1. linear velocity

2. hanging masses

3. linear momentum

4. centripetal force

Q. In which of the following cases does gravitational force act as centripetal force?

1. A ship floating in the sea
2. The Moon revolving round the Earth
3. A leaf falling down a tree
4. The Earth revolving around the Sun

Q.

The centripetal force required by a $1000kg$ car that takes a turn of radius $50m$ at a speed of $36kmph$ is:

1. $1000N$

2. $3500N$

3. $1600N$

4. $2000N$

Q. A body of mass m is moving with a constant speed v on a circular path of radius r. The centripetal force acting on the body is

1. 
   $mvr$
2. 
   $\frac{mv}{r^2}$
3. 
   $\frac{m{v}^2}{r}$
4. 
   $mg$

Q.

Ocean tides are the result of:

1. Gravitational force between earth and venus

2. Gravitational force between earth and moon.

3. Gravitational force between sun and earth.

4. Gravitational force between sun and moon.

Q. A car moves with a constant speed of $10{\text{m s}}^{-1}$ in a circular path of radius $10\text{m}$. The mass of the car is $1000\text{kg}$. The centripetal force for the car is:

1. $10\text{N}$
2. $100\text{N}$
3. $1,000\text{N}$
4. $10,000\text{N}$

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 force of $25N$ is applied at an angle of $60°$in the direction of displacement. Calculate the amount of work done by the force if the displacement of the block is $5m$.

1. $10J$
2. $20J$
3. $40J$
4. $50J$

Q.

In a motor garage, a hydraulic lift is used to lift heavy automobiles such as trucks. The cross-sectional areas of the piston carrying the load and the piston where force is applied are in the ratio 5 : 3. The mass of a truck is 15000 kg.

What is the magnitude of the force applied on the piston to just lift the truck?

1. 9.81 × 10³ N

2. 8.82 × 10⁴ N

3. 5.45× 10⁵ N

4. 2.5× 10⁴ N

Q. The period of a body under SHM is represented by $T=P^a{D}^b{S}^c$,
where P is pressure, D is density and S is surface tension.
The value of a, b and c are:

1. 
2. 
3. 
4. -1, -2, 3

Q.

If a particle is moving along a circle with constant angular acceleration, then comment on the linear acceleration of the particle.

Q. State the source of centripetal force that a planet requries to revolve around the Sun. On what factors does that force depend?

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

Q. Is there any shortcut in gravitation chapter?

Q.

Which force is responsible for the earth revolving around the sun?

Q. What is the order from largest to smallest: galaxy, universe, star, asteroids, planets, moons, solar system?

Q. A bullet of mass $50g$ moving with an initial velocity $100m{s}^{-1}$, strikes a wooden block and comes to rest after penetrating a distance $2cm$ in it. Calculate: (i) initial momentum of the bullet, (ii) final momentum of the bullet.

1. $5$ $kg$ $m$ $s^{-1}$, $5$ $kg$ $m$ $s^{-1}$
2. $5$ $kg$ $m$ $s^{-1}$, $0$ $kg$ $m$ $s^{-1}$
3. $5$ $kg$ $m$ $s^{-1}$, $2.5$ $kg$ $m$ $s^{-1}$
4. $2.5$ $kg$ $m$ $s^{-1}$, $0$ $kg$ $m$ $s^{-1}$

Q. Two satellites 'A' and 'B' go around the earth in circular orbits at heights 6R and 4R respectively from the surface of the earth. Assuming the earth to be a uniform sphere of radius 'R', the ratio of the magnitudes of the velocity of satellite A to satellite B is

1. $\sqrt{\frac{3}{2}}$
2. $\sqrt{\frac{5}{7}}$
3. $\frac{5}{7}$
4. $\frac{3}{2}$

Q.

What happens when the earth loses its gravity it is centripetal or centrifugal force?

Q.

Question 1
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?