Question

A body dropped from height H reaches the ground certain time. From what height should it be dropped to reach the ground in half the time?​

Answer 1

Answer:

Explanation:

The distance traveled by an accelerating body is given by S=U*t+ (0.5*a*t^2). where U is the initial velocity, a is the acceleration of the body and t is the time. So in case of free falling body, U=0, a=9.8 m/s2. It T is the time taken to reach the ground, i.e to travel the distance h, then the distance traveled in T/2 is  

H=(0.5*a* T^2)/4= h/4. This implies the distance of the object above the ground is h-h/4=3h/4

Answer 2

Answer:

a cube of one mile of sea water will have 120 millions tonnes of common salt