Question

A wooden block of mass 10g is dropped on the top of a cliff 100m high. Simultaneously, a bullet of mass 10g is fired from the foot of the cliff upward with a velocity of 100m/s. At what time will the bullet and the wooden block meet ? (g = 9.8 m/s2

Answer 1

concept of vertical motion

Answer 2

The bullet and the wooden block meet after 1 second.

At t=0

Bullet is at 0 m

Block is at 100 m

At t=1

Bullet is at 90.91m (100–9.81)

Bullet velocity is 100m/s but is decelerated because of the gravity and cannot travel 100m.

Let they meet after t second, thus -

If block travels 's' m distance then in same time the bullet will travel = (100-s)m

For the block

s = 0 × t + 1/2 × 10 × t²

For the bullet

100−s = 100 × t + 1/2(−10) × t²

On solving both the equations we will get t = 1 second