☰
✕

Laws of Motion
Question
Wired Faculty App

A moving body of mass m and velocity 3 km/h collides with a rest body ofmass 2 m and stick to it. Now the combined mass starts to move. What will be the combined velocity?

  • 4 km/h

  • 1 km/h

  • 2 km/h

  • 3 km/h

Answer

B.

1 km/h

The law of conservation of momentum states that for two objects colliding in an isolated system, the total momentum before and after collision is equal.

Applying law of conservation of momentum

             m1 v1 = MV

[ m2 v2 = 0 because v2 = 0 and M = m1 + m2 , V = final velocity 

             m × 3 = ( m + 2m ) v1

 So,          v1 = 1 km/h

Sponsor Area

Some More Questions From Laws of Motion Chapter

What is measure of inertia of body?

Which law of motion defines the force?

What happens to a stone tied to the end of string and whirled in a circle if the string suddenly breaks?

Which law of motion gives the quantitative knowledge of force?

Which law of motion is the real law of motion?

Which law of motion gives the quantitative definition of force?

Why do we pull the rope in downward direction for climbing up?

What can set the body at rest into motion?

What do you mean by mechanically isolated system?

What are absolute units of force?