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4 (a) 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
4 (a) 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 ... show full transcript
Worked Solution & Example Answer:4 (a) 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:
Where (\Delta v) is the change in velocity (from 0 m/s to 5 m/s) and (\Delta t) is the change in time (from 0 s to 2 s).
Thus, (a = \frac{5-0}{2-0} = 2.5 , \text{m/s}^2). The unit is m/s².
Step 5
Explain why the upward force from the cable during the first 2 s is greater.
Answer
During the first 2 seconds, the block accelerates upwards, requiring a greater upward force to overcome both the weight of the block and to provide additional force for acceleration. After this period, the block reaches a constant velocity, meaning that the upward force balances out the weight, leading to a reduced force in the subsequent time interval.
Step 6
Explain how the graph shows that the second crane has the larger power.
Answer
The second crane's velocity/time graph shows a greater area under the curve compared to the first crane's graph for the same time interval. This area represents the work done in lifting the load, and since the second crane reaches a higher velocity more quickly, it indicates a larger power output compared to the first crane.