4.5 Energy, work and power · Pull a particle along a slope, send it down a smooth slide or drive a car up a hill, and balance the work done against the energy and power used.
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About this lab
Pull a particle along a slope, send it down a smooth slide or drive a car up a hill, and balance the work done against the energy and power used.
You will be able to
Calculate the work done by a constant force at an angle to the displacement using W = Fd cos θ, and find the gravitational potential energy mgh and the kinetic energy ½mv².
Use the work–energy principle (work done by the driving force − work done against resistance = change in KE + change in PE) to find a speed or the work done against a resistance, including on a smooth curved slide where only the overall energy changes matter.
Calculate average power as work done ÷ time taken, and the power of a force in the direction of motion as P = Fv.
Determine the instantaneous acceleration and the steady speed of a car on a hill from P ÷ v − R − mg sin α = ma.
