A crane is lifting a heavy block from the ground to the top of a building - Edexcel - GCSE Physics - Question 4 - 2012 - Paper 1
Question 4
A crane is lifting a heavy block from the ground to the top of a building.
This is the velocity/time graph for the block as it travels upwards.
For how many second... show full transcript
Worked Solution & Example Answer:A crane is lifting a heavy block from the ground to the top of a building - Edexcel - GCSE Physics - Question 4 - 2012 - Paper 1
Step 1
For how many seconds is the block moving at a constant velocity?
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Answer
The block is moving at a constant velocity for 16 seconds.
Step 2
Draw an arrow on the diagram to represent the weight of the block.
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Answer
A downward arrow should be drawn, starting at the center of the block.
Step 3
Complete the sentence by putting a cross (✗) in the box next to your answer.
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Answer
D zero.
Step 4
Use the velocity/time graph to calculate the acceleration of the block during the first 2 s.
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Answer
To find the acceleration, we use the formula:
a=ΔtΔv
During the first 2 seconds, the velocity changes from 0 m/s to 3 m/s. Therefore,
a=2s3m/s−0m/s=1.5m/s2.
Step 5
Explain why the upward force from the cable during the first 2 s is greater than the upward force for the next 4 s.
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Answer
During the first 2 seconds, the block is accelerating upwards, which means the upward force must be greater than the weight of the block to produce this acceleration. After the initial acceleration, the force becomes equal to the weight, allowing the block to maintain a constant velocity.
Step 6
Explain how the graph shows that the second crane has the larger power.
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Answer
The second crane has a higher gradient in its velocity/time graph which indicates that it reaches a higher velocity in the same time frame compared to the first crane. Since power is related to the rate of doing work or the product of force and velocity, this suggests that the second crane is exerting a greater power to lift the block.
