Question

PHYSICS
16. As is thrown vertically upwards with a speed of 20 ms.The time in seconds) taken by it to come
back to its point of projection is (take g = 10 m​

Answer 1

Heyy Mate Here Is ur Answer....

Let us take the point of projection as the origin of coordinate system. Let the up direction be taken as positive.

The initial velocity of the body = + 20 m/ß

Acceleration due to gravity a= - 10 m/s²

Let the time taken to return to the ground be t second

Since the objects return to the ground, the displacement s= 0 m

Using the relation; s = u × t + ½ a t².

Substituting various values

0 = 20 t - ½ × 10× t²; ==> 20 t - 5 t² = 0;

5 t² - 20 t = 0; ==> 5 t (t - 4) = 0; ==> t= 0 sec. or t = 4 sec.

The body would be at the ground at the beginning ie at t =0 and again at t = 4 s

Hope It helps u :-)