A balloon is at a height of 81 m and is ascending upwards with a velocity of 12 m/s. A body of 2 kg weight is dropped from it. If $g=10m/s^2$, the body will reach the surface of the earth in 

1. 1.5 s

2. 4.025 s

3. 5.4 s

4. 6.75 s

Water drops fall at regular intervals from a tap which is 5 m above the ground. The third drop is leaving the tap at the instant the first drop touches the ground. How far above the ground is the second drop at that instant  

1. 2.50 m

2. 3.75 m

3. 4.00 m

4. 1.25 m

A ball is thrown vertically upwards from the top of a tower at $4.9m{s}^{-1}$. It strikes the pond near the base of the tower after 3 seconds. The height of the tower is:

1. 73.5 m

2. 44.1 m

3. 29.4 m

4. None of these

A rocket is fired upward from the earth's surface such that it creates an acceleration of 19.6 m/sec². If after 5 sec its engine is switched off, the maximum height of the rocket from earth's surface would be [MP PET 1995]

1. 245 m

2. 490 m

3. 980 m

4. 735 m

A body starts to fall freely under gravity. The distances covered by it in the first, second and third second will be in the ratio: 

P, Q and R are three balloons ascending with velocities U, 4U and 8U respectively. If stones of the same mass be dropped from each, when they are at the same height, then 

1. They reach the ground at the same time

2. Stone from P reaches the ground first

3. Stone from R reaches the ground first

4. Stone from Q reaches the ground first

A body falling for 2 seconds covers a distance S equal to that covered in next second. Taking $g=10m/s^2,S=$

1. 30 m

2. 10 m

3. 60 m

4. 20 m

A body dropped from a height h with an initial speed of zero, strikes the ground with a velocity $3km/h$. Another body of the same mass is dropped from the same height h with an initial speed $-u^{\text{'}}=4km/h$. Find the final velocity of the second body with which it strikes the ground.

1. 3 km/h

2. 4 km/h

3. 5 km/h

4. 12 km/h

A ball of mass m₁ and another ball of mass m₂ are dropped from equal height. If time taken by the balls are t₁ and t₂ respectively, then 

1. $t_1=\frac{t_2}{2}$

2. $t_1=t_2$

3. $t_1=4t_2$

4. $t_1=\frac{t_2}{4}$