Momentum
1) What is the equation the links momentum with mass and velocity?
…momentum = mass x velocity ……..(1mark)
2) A car of mass 1000kg is travelling at 15m/s, what is its momentum?
……15000 N s (kg.m/s) …………(1 mark)
3) A 0.5kg trolley A is pushed at a velocity of 1.2m/s into a stationary
trolley B of mass 1.5kg. The two trolleys stick to each other after the
impact. What is the momentum of trolley A before the collision. What
is the velocity of the two trolleys after the collision?
0.6 N s (kg.m/s)
0.3 m/s …(3 marks)
4)
A car is travelling at 10m/s, it hits and stays in contact with another
car of the same mass. What is the resultant speed of the two cars
together? ……
the momentum has to be conserved. If the mass is doubled the velocity
will be halved.
5m/s…(2 marks)
5) Trolley A of mass 2kg is travelling at 0.3m/s. Trolley B of mass 2.5kg
is travelling in the opposite direction at 0.2m/s. The two trolleys collide
and stick together. At what velocity do the trolleys travel after the
collision? …2X0.3 = 0.6 (left) 2.5X0.2 = 0.5 (right) resultant
0.1 (left) 4.5 x ? = 0.1 velocity = 0.02m/s
………………………………………………………………………
…… (3 marks)
6) What equation links change in momentum, time and force? …
force = change in momentum / time (1 mark)
7) A bullet of mass 0.004kg moving at a speed of 90m/s is
stopped by a little bullet-proof vest in 0.0003s. Calculate the
impact force.
0.004 x 90 = 0.36
0.36/0.0003 1200N (2 marks)
8) At turn 8 of the Spanish grand prix Heikki Kovalainen went off
the track at 100miles per hour (45m/s). The car hit the tyre
wall and came to a stop in 0.08s. A F1 car has a mass of
604kg. Calculate the force on the car.
45 x 604 = 27180 27180/0.08 339750 (2 marks)
9) A car of mass 900kg is travelling at 13m/s when it hits another,
stationary, car of mass 750kg. Both cars then collide into a
wall and come to a stop with an acceleration of -0.5m/s2. How
long did it take the cars to com to a complete stop and what
was the force on the cars during this time?
A – 900 x 13 = 11700 kg m/s
f = ma = 1650 x 0.5 = 825N
AB - time = change in momentum/force = 11700/825 = 14.2s
(4 marks)