Make sure that you know these energy transfer scenarios. These are all mentioned in the AQA specification.
1. Object Projected Upwards:
- Initial Energy: The object initially possesses kinetic energy due to its initial velocity.
- During Ascent: As the object moves upward against gravity, its kinetic energy decreases while its gravitational potential energy increases. The total mechanical energy (the sum of these two) remains constant if air resistance is neglected.
- At the Peak: At the highest point, the kinetic energy is minimal (almost zero), and the gravitational potential energy is at its maximum.
- Descending: As the object descends, its gravitational potential energy decreases, while kinetic energy increases. Energy is conserved throughout the motion.
2. Moving Object Hitting an Obstacle:
- Initial Energy: The object has kinetic energy due to its initial motion.
- During Collision: When the object collides with an obstacle, some of its kinetic energy is transferred to the obstacle as kinetic energy, deformation energy, or sound energy. This may result in a loss of kinetic energy in the object.
- After Collision: The object may come to rest if enough energy is transferred to the obstacle and converted into other forms like deformation (if it’s a solid obstacle) or sound.
- Conservation of Total Energy: In a closed system, the total mechanical energy (kinetic + potential) remains constant, even though some energy might change forms.
3. Object Accelerated by a Constant Force:
- Initial Energy: The object has potential energy due to its initial position and kinetic energy if it’s in motion.
- During Acceleration: As a constant force is applied, work is done on the object, converting some of its potential energy or kinetic energy into mechanical work and increasing its kinetic energy.
- Conservation of Energy: The total mechanical energy can change if external forces like friction are involved. Otherwise, in an ideal case, the mechanical energy remains conserved.
4. Vehicle Slowing Down:
- Initial Energy: The vehicle has kinetic energy due to its motion.
- During Deceleration: As the brakes are applied, friction and other forces act in the opposite direction of motion. These forces do work on the vehicle, converting its kinetic energy into heat energy due to friction and mechanical work.
- Final Energy: The vehicle eventually comes to a stop, and its kinetic energy is fully converted into heat and work energy.
5. Bringing Water to a Boil in an Electric Kettle:
- Initial Energy: The electric kettle is supplied with electrical energy from the power source.
- Energy Transfer: The electric kettle’s heating element converts electrical energy into thermal energy. This thermal energy is then transferred to the water through conduction and convection.
- Temperature Rise: As the water absorbs thermal energy, its temperature increases. The energy transferred is used to raise the water’s temperature from room temperature to its boiling point.
- Boiling Point: When the water reaches its boiling point, additional energy input is required to convert the water from a liquid to a gas, which is known as the latent heat of vaporization.
- End Result: The end result is hot, boiling water, and the energy from the electrical source is now primarily in the form of thermal energy in the water.
GCSE Exam Revision Specification Focus Questions and Answers 