Question

Please help me in this question. Please don't give unnecessary answers. ​

Answer 1

Velocity after two seconds

v=u+gt

v=0+9.8×2

v=19.6m/s

Velocity when a ball has fallen through 78.4m is given by

v

2

−u

2

=2gh

v

2

−0=2×9.8×78.4

v

2

=1536.64

v=39.2m/s

Let time taken in falling through 78.4m be ts.

h=ut+

2

1

gt

2

78.4=0×t+

2

1

×9.8×t

2

t

2

=

4.9

78.4

t

2

=16

t=4s

Thus time taken in falling through 78.4m is 4s.