Question

Abullet of mass 10 g moving with velocity
of 1 5 m/s hits a thick wooden plank of mass
90 gm. The plank is initially at rest, but whe
it gets hit by the bullet, the bullet remains
in the plank and both move with a certain
speed. Calculate the speed with which
plank containing the bullet moves.​

Answer 1

Answer:

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Explanation:

Mass of the bullet, m=10gm=0.01kg

Velocity of bullet , v=1.5m/s

Mass of plank, m

p

=90gm=0.09kg

Initial velocity of plank =0m/s

Momentum of the bullet, p=mv=0.01∗1.5=0.015kgm/s

Total mass of the plank =m+m

p

=0.01+0.09=0.1kg

The plank and the bullet both move with the same speed

Momentum of the plank and the embedded bullet is 0.015kgm/s

(∵ the momentum is conserved in a collision.)

But momentum of the plank and the embedded bullet = product of their mass and velocity.

∴0.015=0.1×v

⇒∴v=

0.1

0.015

=0.15m/s

The speed of the plank containing the bullet is 0.15m/s

Answer 2

The speed of the plank containing the bullet is 0.15m/s