Momentum Questions - Solution
Q3. The diagram represents an experiment that can be used to investigate stopping distances for a moving trolley.
The trolley is placed on the raised section of the track. When released it moves down the track and then travels along the horizontal section before colliding with the block. The trolley and block join and move together after the collision. The distance they move is measured.
(a) State the main energy changes taking place
(i) as the trolley descends,
The change is from gravitational potential energy to kinetic energy
(ii) after the collision, as the trolley and block move together.
The change is from kinetic energy to heat energy
(2 marks)
(b) Describe how the speed of the trolley, just before it collides with the block may be measured experimentally.
You could use light gates. Place a piece of card on trolley of measured length. The card obscures light from hitting the light gate just before trolley strikes block . You can then calculate speed (speed = distance/time) from length of card and the time the light signal was obscured.
OR
Measure the horizontal distance of the track travelled and the time it takes to travel it with a stopwatch.Use speed = distance/time to calculate the speed
OR
Measure the height of the ramp ‘ h’and equate potential and kinetic energy ½ mv 2 = m gh so v 2 = 2 gh
OR
Use a data logger + sensorexplain with your system how data was processedand how speed was found
(3 marks)
(c) State and explain how the speed of the trolley, prior to impact could be varied.
You could vary the starting height of trolley [or change angle it was inclined at] . The greater the height (or bigger the angle) the greater the speed of impact
[or alter friction of surfacegreater friction, lower speed]
(2 marks)
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