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
For how many seconds is the block moving at a constant velocity?
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The block is moving at a constant velocity for 16 seconds. This is derived from observing the velocity/time graph where the flat section indicates constant velocity.
Step 2
Draw an arrow on the diagram to represent the weight of the block.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
A downward arrow should be drawn starting from the center of the block. This represents the gravitational force acting on the block.
Step 3
Complete the sentence by putting a cross (✗) in the box next to your answer.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The correct answer is D zero. When the block is moving upwards at a constant velocity, the resultant force is zero because the upward force equals the weight of the block.
Step 4
Use the velocity/time graph to calculate the acceleration of the block during the first 2 s. State the unit.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The acceleration can be calculated using the formula:
a=ΔtΔv
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.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
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.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
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.
