Question

A body is dropped from a height of 20m. Find the final velocity on renting ground [g=10ms square]

Answer 1

Answer:

s = 20m

u = 0 m/s

m = 4 kg

g = 10 m/s²

Initial momentum = mu

= 4×0

= 0 kg m/s

v²-u² = 2as

v²-0² = 2×10×20

v² = 400

v = √400

v = 20 m/s

Final momentum = mv

= 4×20

= 80 kg m/s

Answer 2

Answer:

Given, initial velocity of ball, u=0

Final velocity of ball, v=?

Distance through which the balls falls, s=20m

Acceleration a=10ms

−2

Time of fall, t=?

We know

v

2

−u

2

=2as

or v

2

−0=2×10×20=400 or v=20ms

−1

Now using v=u+at we have

20=0+10×t or t=2s