Question 5
A moving object has a momentum of 6 kg m s−1. If its mass is 500 g, what is its velocity?
The right answer is the one marked above.
12 m s−1. The unknown here is the velocity, so the equation is used in reverse — but convert the mass first:
500 g = 0.5 kg
v = momentum ÷ m = 6 ÷ 0.5 = 12 m s−1
Check it: 0.5 kg × 12 m s−1 = 6 kg m s−1. ✓
3 comes from multiplying by 0.5 instead of dividing. Dividing by a number smaller than 1 must make the answer larger.