GCSE Questions: Momentum
Q5. Thea investigates collisions of trolleys on a horizontal airtrack.
![](graphics/airtrack.png)
Trolley A has a mass of 2kg - - - - - - - - - Trolley B has a mass of 2.5kg
(a) Write down the two quantities involved with motion which are conserved during an elastic collision.
momentum
and kinetic energy ![](../../../../graphics/symbols/nuclides/ticksmall.png)
[2 marks]
(b)
(i) Calculate the momentum of each trolley.
Trolley A
p = mv ![](../../../../graphics/symbols/nuclides/ticksmall.png)
pA = 2 x 4.2
pA = 8.4 kg m/s ![](../../../../graphics/symbols/nuclides/ticksmall.png) |
Trolley B
p = mv
pB = 2.5 x 2.7
pB= 6.75 kg m/s |
[4 marks]
(ii) The two trolleys collide and stick together after the collision.
Use your answers to (b)(i) to calculate the speed of the combined trolleys after the collision.
Record your answer to 2 significant figures
Σp (before collision) = Σp (after collision)
pA + pB = pA+B
pA+B = 8.4 + 6.75 = 15.15 ![](../../../../graphics/symbols/nuclides/ticksmall.png)
pA+B = mA+B x vA+B
15.15 = (2 + 2.5) vA+B
vA+B = 15.15/4.5 ![](../../../../graphics/symbols/nuclides/ticksmall.png)
vA+B = 3.367 ![](../../../../graphics/symbols/nuclides/ticksmall.png)
vA+B = 3.4 m/s ![](../../../../graphics/symbols/nuclides/ticksmall.png)
[4 marks]
[10 Marks TOTAL]