A stone is dropped from a height \(h\). Simultaneously, another stone is thrown up from the ground which reaches a height \(4h\). The two stones cross each other after time:
1. \(\sqrt{\frac{h}{8g}}\)
2. \(\sqrt{8g}~h\)
3. \(\sqrt{2g}~h\)
4. \(\sqrt{\frac{h}{2g}}\)

Four marbles are dropped from the top of a tower one after the other at a one-second interval. The first one reaches the ground after \(4\) seconds. When the first one reaches the ground the distances between the first and second, the second and third, and the third and fourth will be, respectively:

A balloon rises from rest with a constant acceleration g/8. A stone is released from it when it has risen to height h. The time taken by the stone to reach the ground is

(1) $4\sqrt{\frac{h}{g}}$

(2) $2\sqrt{\frac{h}{g}}$

(3) $\sqrt{\frac{2h}{g}}$

(4) $\sqrt{\frac{g}{h}}$ 

Two bodies are thrown simultaneously from a tower with same initial velocity v₀ : one vertically upwards, the other vertically downwards. The distance between the two bodies after time t is

(1) $2v_{0}t+\frac{1}{2}g{t}^2$

(2) 2v₀t

(3) $v_{0}t+\frac{1}{2}g{t}^2$

(4) v₀t

A body falls freely from the top of a tower. It covers 36% of the total height in the last second before striking the ground level. The height of the tower is:

(1) 50 m

(2) 75 m

(3) 100 m

(4) 125 m

A particle is projected upwards. The times corresponding to height \(h\) while ascending and while descending are t₁ and t₂ respectively. The velocity of projection will be:
1. \(gt_1\)
2. \(gt_2\)
3. \(g(t_1+t_2)\)
4. \(\frac{g(t_1+t_2)}{2}\)

A projectile is fired vertically upwards with an initial velocity u. After an interval of T seconds a second projectile is fired vertically upwards, also with initial velocity u.

(1) They meet at time $t=\frac{u}{g}$ and at a height $\frac{u^2}{2g}+\frac{g{T}^2}{8}$

(2) They meet at time $t=\frac{u}{g}+\frac{T}{2}$ and at a height $\frac{u^2}{2g}+\frac{g{T}^2}{8}$

(3) They meet at time $t=\frac{u}{g}+\frac{T}{2}$ and at a height $\frac{u^2}{2g}-\frac{g{T}^2}{8}$

(4) They never meet

Two cars are moving in the same direction with the same speed \(30\) km/hr. They are separated by a distance of \(5\) km. The speed of a car moving in the opposite direction, if it meets these two cars at an interval of \(4\) minutes, will be:
1. \(40\) km/hr
2. \(45\) km/hr
3. \(30\) km/hr
4. \(15\) km/hr

A 150 m long train is moving to north at a speed of 10 m/s. A parrot flying towards south with a speed of 5 m/s crosses the train. The time taken by the parrot the cross to train would be: 

(1) 30 s

(2) 15 s

(3) 8 s

(4) 10 s

Two trains along the same straight rails moving with constant speed 60 km/hr and 30 km/hr respectively towards each other. If at time t = 0, the distance between them is 90 km, the time when they collide is:

1. 1 hr

2. 2 hr

3. 3 hr

4. 4 hr