A sprinter starts from rest and accelerates uniformly for 3 seconds until she reaches a velocity of 10 m s⁻¹ - Leaving Cert Physics - Question b - 2016
Question b
A sprinter starts from rest and accelerates uniformly for 3 seconds until she reaches a velocity of 10 m s⁻¹. She then runs at a constant velocity for 6 seconds befo... show full transcript
Worked Solution & Example Answer:A sprinter starts from rest and accelerates uniformly for 3 seconds until she reaches a velocity of 10 m s⁻¹ - Leaving Cert Physics - Question b - 2016
Step 1
Labelled Axes
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Answer
Begin by sketching the velocity-time graph with the vertical axis representing velocity (in m/s) and the horizontal axis representing time (in seconds). Mark appropriate scales for both axes.
Step 2
Correct Acceleration
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Answer
During the first 3 seconds, the sprinter accelerates from rest (0 m/s) to 10 m/s. The acceleration (a) can be calculated using the formula:
a=ΔtΔv=3s10m/s−0m/s=310m/s2
This portion of the graph will be a straight line from (0, 0) to (3, 10).
Step 3
Correct Constant Velocity
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Answer
For the next 6 seconds, the sprinter runs at a constant velocity of 10 m/s. This will be represented as a horizontal line on the graph from (3, 10) to (9, 10).
Step 4
Correct Deceleration
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Answer
After 9 seconds, the sprinter decelerates until she comes to a stop. If we assume she takes the same time to decelerate, the graph will have a line sloping down from (9, 10) to (12, 0).
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