A balloon with mass $15\,\text{g}$ is attached to a straw. The straw is threaded onto a horizontal string, as shown in Fig. 3.1. The diagram identifies horizontal string, hollow straw fixed to balloon, balloon, and direction of motion of balloon. The balloon is inflated with air and then the air is let out. As the air leaves the balloon, the balloon experiences a force. It accelerates from rest until it reaches a constant speed. It then travels $0.67\,\text{m}$ in $0.18\,\text{s}$ at this constant speed.
(a(i))[1]
Explain, in words, what is meant by the term impulse.
(a(ii))[3]
Calculate the net impulse on the balloon while it is speeding up.
(a(iii))[2]
Explain how momentum is conserved while the balloon accelerates.
(b)[4]
Determine the magnitude and direction of the resultant force on the balloon.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Force \times time over the interval during which the force acts” …