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| Question | Answer |
| What are the eight different energy stores? Give an example of each. | Kinetic (KE = 1/2mv^2), Elastic potential, Electrostatic, Thermal, Magnetic, Chemical, Gravitational Potential (Change in GPE = mg(Change in h)), Nuclear |
| Give the energy store that increases in each of these examples: (3 marks) (a) when a mass is lifted through a height (b) when a pan of water at 20ºC water is heated to 70ºC (c) when an extra cell is added to a circuit. | (a) g. p e. (b) thermal (c) chemical |
| A kettle has a power rating of ® W. How much energy does it use in √ seconds? | ®√ J |
| Wind turbines are designed to use the kinetic energy of moving air to turn the turbine blades. Explain why this is described as a mechanical process and, therefore, why efficiency is important. (6 marks) | This is decribed as a MECHANICAL PROCESS because the turbine is moves by the KINETIC ENERGY of the moving air. (1) Mechanical energy is the sum of POTENIAL and kinetic ENEGY. (1) The mechanical enegry of the moving air gives the air particles the ability to apply a force and cause a displacement of the blades. (1) Mechanical processes become wasteful when they cause a rise in temperature so DISSIPATING energy to the THERMAL store of the eviroment. (1) Rise in temperature is caused by FRICTION betwn moving objects / materials. (1) It is important to keep frictn as low as posible to minimise wasted enegy. (1) By reducing waster enegy the wind turbns can be made more efcient. (1) HIGHER EFFICIENCY WILL MEAN MORE ELCTRICITY IS GENRATED. (1) |
| Walking uphill Al walks directly up a hill and he takes 12 minutes to get to the top. Bev walks up the same hill on a shallower path that zig zags as it goes up. She takes 15 minutes to get to the top. Explain who has exerted the greater power, and who has transferred more energy while getting to the top of the hill. Include any assumptions you make in your answer. (6 marks) | Student answer Power is the work of doing work, and is measured in watts. In watts. In climbing the hill, they are doing work against gravity, and the energy transferred is the force (their weight) multiplied by the distance moved in the direction of the force (up the hill). In theory they've transferred the same energy. (Assume they have the same weight). Power = Work/Time, so Al exerted the greater power. They're weights may not be the same though, and Bev wasted more energy as she was walking for longer. |
| Give the three types of fields that cause objects to interact with each other without making contact. | Gravitational, electrostatic, and magnetic. |
| Explain which of these is different from the other two and why. | grav. fields are different because they only attract wheras magnetc and elecrostatc fiels atract and repel. |
| Why are weight and normal contact force vectors. (2 marks) | Wieght has a direction (downwards). (1) Normal contact force is a vector bcse it has a direction (upwards/opposite to wight). (1) |
| Which of the following is not one of the steps for resolving a resultant force using a scale drawing? A The angles are drawn with a protractor. B The scale is not important. C The vertical component can be found through measurement. D The horizontal line is drawn to scale. (1 mark) | B |
| Draw a free-body diagram to represent a cyclist accelerating to the left along a horizontal path. | 1 mark for each arrow. The longest arrow should be to the left. |
| Balanced and resultant forces are an important consideration when operating a camera drone remotely. To film an aerial sequence, the camera operator flies the drone to the required height for filming and keeps it stationary by controlling the speed of the rotor blades. Explain the balanced or unbalanced forces acting on the camera drone during operation (assume breeze is negligible). (6 marks) | When the drone takes off the downwards force of the rotor blade creates a reaction force (Newton's third law). (1) The reaction force is greater than the downwards force of the weight of the drone and it moves upwards. (1) The vertical resultant force continues during the flight of the drone. (1) The height can be adjusted by increasing or decreasing the upwards reaction force (due to the rotor blades). (1) To move to a location, an additional resultant horizontal force is required. (1) As the drone flies horizontally, the thrust of the drone must be greater than the air resistance acting in the opposite direction. (1) When these two are balanced or zero the drone will hover. (1) |
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