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Resultant Force on a Raised Runway
The runway was then raised at one end. The force acting through the string remained the same. Figure 11 shows this.
Explain how the acceleration was affected by raising the end of the runway.
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Marking points
- 1 Identifies a component of the trolley's weight acting parallel to the runway, or gives the accepted energy-transfer route.
- 2 Concludes that the resultant force and acceleration increase, or completes the accepted energy-transfer link.
Full-mark answer
Raising the runway gives the trolley's weight a component down the runway in the same direction as the pull. The resultant force is therefore larger, so the trolley's acceleration increases.
Why this answer loses marks
Raising the runway makes the trolley heavier, so it speeds up.
The trolley’s mass and weight do not increase; a component of its existing weight acts along the slope and increases the resultant force.