Question

A bullet of mass 20 g is fired vertically upward with a velocity 50 m/s. After what time it will reach the

ground?​

Answer 1

k.e = mv² / 2

==> 0.02 × 2500 / 2

==> 2500 × 0.01

==> 25 J

k.e = mgh ( maximum height )

25 = 0.02 × 10 × h

h = 25/0.2

h = 125 m

h = ut + 1/2 gt²

125 = 0t + 10t² / 2

125 = 5t²

t² = 25

t = 5 or -5

time can't be negative , so t = -5 is neglected.

Hence, Time taken will be (5 + 5) == >10 s