Why Gravitational Field

Q.

The kinetic energy of a body becomes twice its initial value. The new momentum of the body will be

1. $2$ times

2. $\sqrt{2}$ times

3. $4$ times

4. unchanged

Q. A ball of mass $5\text{kg}$ moving at speed $2\text{m/s}$ makes a head on collision with an identical ball at rest. The velocities of the balls after the perfectly elastic collision between them are respectively:-

1. $1\text{m/s},1\text{m/s}$
2. $0\text{m/s},2\text{m/s}$
3. $1.2\text{m/s},0.5\text{m/s}$
4. $1.5\text{m/s},0.2\text{m/s}$

Q.

A truck and a car are running at same velocity. If the mass of truck is $10times$ that of car , the ratio of kinetic energy of truck and car is:

1. $1:10$

2. $2:5$

3. $10:1$

4. $5:2$

Q. A particle of mass ${}^{\prime }{m}^{\prime }$ is moving with speed $8\text{m/s}$ on a frictionless surface as shown in figure. If $m<<M$, then for one dimensional elastic collision, the speed of the lighter particle after collision will be

1. $4\text{m/s}$ in original direction
2. $4\text{m/s}$ opposite to the original direction
3. $6\text{m/s}$ in original direction
4. $6\text{m/s}$ opposite to the original direction.

Q. In the figure shown below, two particles have masses $2\text{kg}$ each and they are moving with velocities $4\text{m/s}$ and $2\text{m/s}$ respectively towards each other. Assume the collision between the particles is perfectly elastic. Find their respective magnitudes of velocities after the collision.

1. $v_1=3\text{m/s};v_2=3\text{m/s}$
2. $v_1=2\text{m/s};v_2=3\text{m/s}$
3. $v_1=2\text{m/s};v_2=4\text{m/s}$
4. $v_1=4\text{m/s};v_2=4\text{m/s}$

Q. A ball of mass 'm' moving horizontally at a speed 'v' collides with the bob of a simple pendulum at rest. The mass of the bob is also' 'm, if the collision is perfectly elastic, the bob of the pendulum will rise to a height of

1. $\frac{v^2}{g}$
2. $\frac{v^2}{2g}$
3. $\frac{v^2}{4g}$
4. $\frac{v^2}{8g}$

Q. In the given figure, all the collisions are elastic. Find the velocity of $n^{th}$ ball after collision.

1. $2^{n-1}u$
2. $3^{n-1}u$
3. ${\left(\frac{2}{3}\right)}^{n-1}u$
4. ${\left(\frac{3}{2}\right)}^{n-1}u$