Question
The momentum of an object changes by Δp in a time Δt. What is the impulse acting on the object during this change?
A. Δp
B. Δp Δt
C. \(\frac{{\Delta p}}{{\Delta t}}\)
D. zero
Answer/Explanation
Markscheme
A
Question
A cyclist accelerates in a straight line. At one instant, when the cyclist is exerting a forward force of 40 N, the air resistance acting on the cyclist is 10 N.
What is the rate of change of momentum of the cyclist at this instant?
A. 10 kg m s–2
B. 30 kg m s–2
C. 40 kg m s–2
D. 50 kg m s–2
Answer/Explanation
Markscheme
B
Question
A toy car of mass 0.15 kg accelerates from a speed of 10 cm s–1 to a speed of 15 cm s–1. What is the impulse acting on the car?
A. 7.5 mN s
B. 37.5 mN s
C. 0.75 N s
D. 3.75 N s
Answer/Explanation
Markscheme
A
Question
A stopper of mass 8 g leaves the opening of a container that contains pressurized gas.The stopper accelerates from rest for a time of 16 ms and leaves the container at a speed of 20 m s–1.
What is the order of magnitude of the force acting on the stopper?
A. 10–3 N
B. 100 N
C. 101 N
D. 103 N
Answer/Explanation
Markscheme
C
Question
A ball of mass m collides with a vertical wall with an initial horizontal speed u and rebounds with a horizontal speed v. The graph shows the variation of the speed of the ball with time.
What is the magnitude of the mean net force on the ball during the collision?
A. \(\frac{{m(u – v)}}{{({t_2} + {t_1})}}\)
B. \(\frac{{m(u – v)}}{{({t_2} – {t_1})}}\)
C. \(\frac{{m(u + v)}}{{({t_2} + {t_1})}}\)
D. \(\frac{{m(u + v)}}{{({t_2} – {t_1})}}\)
Answer/Explanation
Markscheme
D