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A moving tram is powered by energy stored in a rapidly spinning flywheel - AQA - A-Level Physics - Question 2 - 2022 - Paper 6
Question 2
A moving tram is powered by energy stored in a rapidly spinning flywheel. When the tram is at a tram stop, the flywheel is 'charged' by being accelerated to a high ... show full transcript
Worked Solution & Example Answer:A moving tram is powered by energy stored in a rapidly spinning flywheel - AQA - A-Level Physics - Question 2 - 2022 - Paper 6
Step 1
Calculate the minimum angular speed of the flywheel when the tram leaves stop A so that the tram reaches stop B using only energy stored in the flywheel.
Answer
To find the minimum angular speed of the flywheel, we can use energy conservation principles. The work done by the resistance forces while the tram travels 500 m up the incline is:
The energy used to overcome resistance is stored in the flywheel:
W = rac{1}{2} I heta^2
Where:
- is the moment of inertia of the flywheel,
- is the angular displacement.
Now substituting the values:
-
Calculate the work done:
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Using the moment of inertia and knowing the radius (diameter of 1.00 m), we can substitute: 5.9 imes 10^5 = rac{1}{2} imes 62.5 imes (0.5 imes heta)^2
-
Simplifying gives:
-
Solving for gives the angular speed:
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Finally, calculate .
Step 2
Suggest two advantages of keeping the flywheel connected to the driving wheels when the tram travels downhill.
Answer
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Energy Recovery: When the tram travels downhill, the flywheel can act as a regenerative brake. The kinetic energy generated during the downhill motion can be transformed back into potential energy, storing it within the flywheel for later use, thereby improving energy efficiency.
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Stability Control: Connecting the flywheel to the driving wheels can provide additional stability to the tram while descending. The rotational inertia of the flywheel helps to reduce sudden shifts, leading to a smoother ride for passengers.
Step 3
Discuss the design features of the flywheel that will enable it to store more energy without increasing the mass of the tram.
Answer
To enhance the energy storage capacity of the flywheel, consider the following design features:
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Material Selection: Using advanced materials with high strength-to-weight ratios, such as carbon fiber or specialized alloys, can allow for a lighter flywheel while maintaining high structural integrity.
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Increased Diameter: A larger diameter flywheel can store more kinetic energy, as the moment of inertia increases with the radius squared. This allows for greater energy storage without necessarily increasing mass significantly.
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Design Shape: Utilizing a more aerodynamic or optimized shape can reduce drag and enhance performance during acceleration and braking, allowing better use of energy stored.
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High RPM Capability: Designing the flywheel to withstand higher rotational speeds increases the kinetic energy stored. This can be achieved through advanced bearings and a more robust construction.
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Modular Design: Implementing a modular design allows the flywheel system to have components that can be upgraded without replacing the entire assembly, aiding in future enhancements for energy storage capabilities.
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Enhanced Cooling Mechanisms: As energy storage capabilities are enhanced, heat generation may increase. Effective cooling systems can prevent overheating, enabling sustained performance at higher energy levels.