Question

Two balls with same mass are dropped from a certain height ...
the final velocity of a ball is 3km/h
and the initial velocity of second ball is 4km/h ....
Find the velocity at which the second ball will strike the ground ....
​

Answer 1

Time taken by first ball to reach the ground is

T

=

√

2

H

g

=

√

2 × 20.0 m

10 m/s

2

=

2 s

Time taken by second ball to reach the ground

=

2 s

−

1 s

=

1 s

For second ball

S

=

u

t

+

1

2

a

t

2

20.0 m

=

(

u

×

1 s

)

+

(

1

2

×

10 m/s

2

×

(

1 s

)

2

)

20 = u + 5

u = 15 m/s