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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. This diagram shows ... 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
Step 2
Step 3
Step 4
Use the velocity/time graph to calculate the acceleration of the block during the first 2 s. State the unit.
Answer
The acceleration can be calculated using the formula:
ext{acceleration} = rac{ ext{change in velocity}}{ ext{time}} = rac{5 - 0}{2 - 0} = rac{5}{2} = 2.5
The unit of acceleration is m/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.
Answer
During the first 2 seconds, the block accelerates upwards, which requires a greater upward force from the cable to overcome both the weight of the block and provide the necessary acceleration. In the following 4 seconds, the block moves at a constant velocity, meaning there is no acceleration. Thus, the upward force needed from the cable only needs to match the weight of the block.
Step 6
Explain how the graph shows that the second crane has the larger power.
Answer
The second crane operates at a higher maximum velocity compared to the first crane, as indicated by the higher peak in the velocity/time graph. Power is the rate at which work is done, and since the second crane is lifting the block to the same height but at a higher velocity, it does the same amount of work in less time, demonstrating a higher power output.