Question

A boy dropped a ball from the top of 20 m building and starts the stopwatch. What will be the reading of<br />stopwatch when ball will reach at ground surface, if acceleration due to gravity is 10 m/s??​

Answer 1

Answer:

we know,

S = ut + 1/2*a*t*t

a is not given,

a = (v - u) / t

= (10 - 0)m/s / t

= 10/t

S = ut + 1/2 * a * t * t

20m = 0 + 1/2 * 10/t * t * t

20 = 5t

t = 20/5s = 4s

hope it will help you............

Answer 2

Answer:

2 second

Explanation:

given= distance travelled=20m .a=g

g=10m/second square

u=0(downward motion)