Question

34. A stone is thrown horizontally with speed of 5 m/s
from top of a building of height 20 m. Time taken
by the body to reach ground is (g = 10 m/s?)
(1) 4 s
(2) 2s
(3) 5s
(4) 3 s
​

Answer 1

Answer:

4 seconds

Explanation:

height of building/speed of stone 20 /5 =4 seconds

Answer 2

Answer:

2 seconds.

Explanation:

Since, the body is thrown from the building and it is having vertical components. So, the initial velocity will be 0 m/s. Since, horizontal components is omitted while throwing a body from a height.

Hence, applying newtons second law of motion we will get.

Time s=5*0 + 1/2gt^2. Here g is 10m/s^2 and distance or the height s=20m.

So, t=√(2*20/10) or time taken will be 2 second.