P3 Physics Work and Power

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• Created by: A.P
• Created on: 20-01-13 10:15
• Work and Power
• Work
• Work is done when a force moves an object in the direction in which the force acts.
• Work done (J) = Energy Transferred (J)
• Work done = Force x Distance Moved
• Power
• Power is the rate at which work is done.
• Power = Work Done / Time Taken
• A person's power is greater when they run than when they walk.
• Power is also relate to force and speed.
• = Power
• = Work Done / Time Taken
• = (Force x Distance) / Time Taken
• = Force x (Distance / Time)
• Force x Speed
• Some cars are more powerful than others. They travel faster and cover the same distance in a shorter time and require more fuel. The power rating of a car depends on its engine size. More powerful cars have greater fuel consumption.
• Fuel is expensive and a car with high fuel consumption is expensive to run.
• Fuel pollutes the environment.
• Car exhaust gases, especially carbon dioxide are harmful.
• Carbon dioxide is also a major source of greenhouse gases, which contribute to climate change.
• Weight
• Weight is a measure of the gravitational attraction on a body acting towards the centre of the Earth.
• Weight = Mass x Gravitational Field Strength
• A mass of 1 kg has a weight of about 10N on Earth.