# A ball of mass 0.5kg moving at 10ms⁻¹ collides with…

Posted by: 789 views

A. 0.2ms⁻¹

B. 0.5ms⁻¹

C. 5.0ms⁻¹

D. 5.5ms⁻¹

C

## DETAILS…

Please note that momentum before impact must be = momentum after impact. This is the law of conservation of momentum.

### Data given:

Mass of ball 1 (M₁) = 0.5kg

Mass of ball 2 (M₂) = 0.5kg

Velocity of ball 1 before collision (V₁) = 10 ms⁻¹

Velocity of ball 2 before collision (V₂) = 0 (since we were told it was at rest)

Common velocity after impact (V₃) =?

Total momentum before impact

= M₁V₁ + M₂V₂

= (0.5 × 10) + (0.5 × 0)

= 5 + 0

= 5kgm/s

Total momentum after impact

= (M₁ + M₂)V₃ (since they sticked together after impact)

= (0.5 + 0.5)V₃

= (1)V₃

= V₃

If momentum before impact = momentum after impact, then

5 = V₃

V₃ = 5m/s

### Now for the right answer to the above question:

1. Option A is incorrect.
2. Option B is incorrect.
3. C is correct.
4. D is not the correct answer.

## KEY-POINTS…

• The law of conservation of momentum is important here.
• Total momentum before impact = total momentum after impact.
• A body at rest has a velocity of zero.
• If the bodies stick together after the collision, the new mass becomes equal to the simple addition of the masses coming together.

If you love our answers, you can simply join our community and also provide answers like this, fellow learners like you will appreciate it.

/ culled from 2021 JAMB-UTME PHYSICS question 4 /

1. +1 Votes 0 Votes 0 Votes