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Figure 21 shows a pulley system that enables a person to lift a heavy barrel - Edexcel - GCSE Physics - Question 9 - 2023 - Paper 2
Question 9
Figure 21 shows a pulley system that enables a person to lift a heavy barrel. The person pulls down on the rope to make the barrel rise through 1.2 m. The work done... show full transcript
Worked Solution & Example Answer:Figure 21 shows a pulley system that enables a person to lift a heavy barrel - Edexcel - GCSE Physics - Question 9 - 2023 - Paper 2
Step 1
(i) Calculate the weight of the barrel.
Answer
To calculate the weight of the barrel, we use the formula:
Given:
- Work done = 1800 J
- Distance = 1.2 m
Rearranging the formula gives:
ext{force} = rac{ ext{work done}}{ ext{distance}} = rac{1800}{1.2} = 1500 ext{ N}Thus, the weight of the barrel is 1500 N.
Step 2
(ii) Calculate the total work done by the person.
Answer
Using the efficiency formula:
ext{efficiency} = rac{ ext{work done against gravity on the barrel}}{ ext{total work done by the person}} imes 100Substituting the known values:
- Efficiency = 64%
- Work done against gravity = 1800 J
Rearranging for total work done:
ext{total work done} = rac{ ext{work done against gravity} imes 100}{ ext{efficiency}} = rac{1800 imes 100}{64} = 2812.5 ext{ J}Therefore, the total work done by the person is approximately 2812.5 J.
Step 3
(iii) Suggest another reason why some energy is wasted in using this pulley system.
Answer
Another reason why energy may be wasted in this pulley system is due to the mass of the pulley itself. The weight of the pulley can add resistance to the system, leading to energy loss as heat due to friction in its bearings.
Step 4
Devise an experiment to investigate how the efficiency of the pulley system varies with the weight of metal being lifted.
Answer
Experiment to Investigate Efficiency of Pulley System
Aim
To determine how the efficiency of the pulley system changes as different weights of metal are lifted.
Equipment
- Spring balance
- Cubes of metal with varying weights
- Meter rule
Procedure
- Setup: Attach a spring balance to one end of the pulley system, and place the metal cubes on the opposite end.
- Measure Weight: Use the spring balance to measure the weight of the metal cube being lifted.
- Record Reading: Note the reading shown on the spring balance when the cube is lifted, indicating the force applied.
- Measure Distance: Measure the distance the metal cube is lifted using the meter rule.
- Calculate Work Done on Metal Cube:
- Work done = weight × distance lifted
- Calculate Work Done by Student: Collect data over several trials with increasing weights of the metal cubes, recording the work done by the student using the spring balance readings and distances.
- Calculate Efficiency: For each weight of cube, calculate the efficiency using:
- Efficiency = (work done against gravity / work done by student) × 100
- Graph Results: Plot a graph of efficiency against the weight of the metal cubes to observe any trends.
Conclusion
Analyze the results to see how the efficiency varies with the weight lifted and any patterns that emerge from the data collected.