Question

A child in a boat throws a 6.6kg package out horizontally with a speed of 10.2m/s. Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the child is 29.9kg, and that of the boat is 44.7kg. Ignore water resistance.

Answer 1

Answer:

$-0.902 \frac ms$

Explanation:

We apply conservation of momentum here. Before the toss, everything was still, so the momentum was 0. After the toss, we have the sum of the momentum of the package (1st term) and the boat+child combo (2nd term). Let's call v the velocity of the boat.

$0= 6.6kg \cdot 10.2\frac ms + (29.9+44.7)kg\cdot v\\v= - \frac{6.6 \cdot 10.2 }{74.6} \frac ms \approx -0.902 \frac ms$

The term is negative since it expresses the boat+child system is going the opposite way from where the package flew.