![]() The engine of the car is working at a constant rate of 5kW. Power is the rate at which work is done (measured in watts (W)), in other words the work done per second.įor example, if the engine of a car is working at a constant rate of 10kW, the forward force generated is power/velocity = 10 000 / v, where v is the velocity of the car (the 10 was changed to 10 000 so that we are using the standard unit of W rather than kW).Ī car of mass 500kg is travelling along a horizontal road. ![]() For example, the work done against gravity is equal to the change in the potential energy of the body and the work done against all resistive forces is equal to the change in the total energy. In other words, the work done is equal to the change in energy. If energy is not conserved, then it is used to do work. If gravity is the only external force which does work on a body, then the total energy of the body will remain the same, a property known as the conservation of energy. Basically, the total potential energy measures the energy of the body due to its position. There are also other types of potential energy (such as elastic potential energy). Where h is the height of the body above the ground. Gravitational potential energy (G.P.E.) is the energy a body has because of its height above the ground. Where m is the mass and v is the velocity of the body. A body which isn't moving will have zero kinetic energy, therefore. The kinetic energy (K.E.) of a body is the energy a body has as a result of its motion. ![]() The energy of a body is a measure its ability to do work. This is equal to mgs joules, where s is the vertical distance moved by the body, m is the mass of the body and g is the acceleration due to gravity. We call the work done by the force the "work done against gravity". Now suppose that the force we are considering is one which causes a body to be lifted off of the ground. If the body moves a distance of s metres along the ground, then the work done is F cosa × s (since F cosa is the component of the force in the direction of motion). Now suppose that this force is at an angle of a to the horizontal. So if we have a constant force of magnitude F newtons, which moves a body a distance s (meters) along a flat surface, the work done is F × s joules. Work done is measured in joules (which has symbol J). Then the work done by the force is the component of F in the direction of motion × the distance the body moves as a result. Suppose a force F acts on a body, causing it to move in a particular direction. Am I paying a lot on electrical bill for charging my phone?Ģ015 2016 2017 2018 2019 2020 COE Comics conduction conservation of energy Current Electricity density displacement-time graph dynamics earth wire electromagnetism FLHR friction fuse GCE GPE hydraulic system KE Kinematics lens light longitudinal waves moments Newton's 1st Law P1 Physics physics comics power practical electricity pressure project radiation reflection refraction resultant force sound terminal velocity thermal transfer things around us tickertape timer Topic Current Electricity Topic DC Topic Direct Current Topic Dynamics Topic Electromagnetic Induction Topic Electromagnetic Spectrum Topic Electromagnetism Topic Energy Work Done Power Topic General Wave Properties Topic Kinematics Topic Kinetic Theory of Matter Topic Light Topic Magnetism Topic Mass Weight Density Topic Moments Topic Practical Electricity Topic Pressure Topic Sound Topic Static Electricity Topic Thermal Properties of Matter Topic Transfer of Thermal Energy total internal reflection transformer transverse waves typography vector diagram velocity-time graph video Videos waves Archives Archives MetaĬreate a free website or blog at section covers Work, Energy and Power using maths.
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