Question

Two objects, each of mass 1.0 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 ms^-1 before the
collision. they sticked together after collision. What will be the velocity of the combined object after collision?

• A. 0 ms^-1
• B. 1 ms^-1
• C. 4 ms^-1
• D. 2 ms^-1

Answer 1

The correct option is A

0 ms^-1

Let the object be A and B moving from opposite direction in the same straight line.

Step 1: Calculate the momentum of A

Momentum of A = m × v

= 1.0 x2.5 = 2.5 kg ms^–1

Step 2: Calculate the momentum of B

Also, Momentum of B

= m × (–v)

=1.0× (–2.5)
= – 2.5 kg ms^–1.

If, v is the velocity of the objects after collision, then the Combined momentum after collision = 3 × v

Using the law of conservation of momentum

Combined momentum of A and B = Momentum of A + Momentum of B

3 × v = 2.5–2.5

3 × v = 0

v = 0