## Question

A ball is thrown vertically downward with a velocity *u* from the top of a tower. It strikes the ground with a velocity 3*u*. The time taken by the ball to reach the ground is given by

### Solution

From,

,

We have

or

#### SIMILAR QUESTIONS

A car, starting from rest, accelerates at a constant rate of 5 ms^{–2} for some time. It then retards at a constant rate of 10 ms^{–2} and finally comes to rest. If the total taken is 6 *s*, What is the maximum speed attained by the car?

A body, starting from rest, moves in a straight line with a constant acceleration *a* for a time interval *t* during which it travels a distance *s*_{1}. If continues to move with the same acceleration for the next time interval *t*during which it travels a distance *s*_{2}. The relation between *s*_{1} and *s*_{2} is

A stone is dropped from a height of 125 m. If *g* = 10 ms^{–2}, what is the ratio of the distances traveled by it during the first and the last second of its motion?

A body, moving in a straight line, with an initial velocity *u* and a constant acceleration *a*, covers a distance of 40 m in the 4^{th} second and a distance of 60 m in the 6^{th} second. The values of *u* and *a* respectively are

A simple pendulum is hanging from the ceiling of a compartment of a train. It is observed that the string is inclined towards the rear of the train. If follows that the train is

The displacement of a body from a reference point, is given by

where *x* is in metres and *t* in seconds. This shown that the body is

A car moving at a speed *v* is stopped in a certain distance when the brakes produce a deceleration *a*. If the speed of the car was *nv*, what must be the deceleration of the car to stop it in the same distance and in the same time?

A car is moving at a certain speed. The minimum distance over which it can be stopped is *x*. If the speed of the car is doubled, what will be the minimum distance over which the car can be stopped during the same time?

The distance *x* covered by a body moving in a straight line in time *t* is given by

The acceleration of the body will vary as

Ball is called in a straight line with a speed of 5 ms^{–1} towards a bigger ball*B* lying 20 m away. After collision with ball *B*, full *A* retraces the path and reaches its starting point with a speed of 4 ms^{–1}. What is the average velocity of ball *A* during the time interval 0 to 6 s?