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. $t_1=\frac{t_2}{4}$ 

With what velocity a ball be projected vertically so that the distance covered by it in 5^th second is twice the distance it covers in its 6^th second $(g=10m/s^2)$ 

1. 58.8 m/s

2. 49 m/s

3. 65 m/s

4. 19.6 m/s

A ball is dropped downwards. After 1 second another ball is dropped downwards from the same point. What is the distance between them after 3 seconds 

1.  25 m
2.  20 m
3.  50 m
4.  9.8 m

A stone is thrown with an initial speed of 4.9 m/s from a bridge in vertically upward direction. It falls down in water after 2 sec. The height of the bridge is 

1. 4.9 m

2. 9.8 m

3. 19.8 m

4. 24.7 m

A stone is shot straight upward with a speed of 20 m/sec from a tower 200 m high. The speed with which it strikes the ground is approximately 

1. 60 m/sec

2. 65 m/sec

3. 70 m/sec

4. 75 m/sec

A body freely falling from the rest has a velocity ‘v’ after it falls through a height ‘h’. The distance it has to fall down for its velocity to become double, is 

1. 2 h

2. 4 h

3. 6 h

4. 8 h