Sunday, December 27, 2009

How much energy is needed to accelerate an 1100kg object along a flat frictionless surface......?

How much energy is needed to accelerate an 1100kg object along a flat frictionless surface from 15km/h to 25km/h in 5.0s?





please show me how to do this question and not just the answer for future testHow much energy is needed to accelerate an 1100kg object along a flat frictionless surface......?
Find the Change in Kinetic Energy





Convert units from km/hr to m/s


vi = 15 km/hr = 15 km/hr * (1000 m/km) * (1/3600 hr/s)


vf = 25 km/hr = 25 km/hr * (1000 m/km) * (1/3600 hr/s)





Work done = change in kinetic energy = 1/2*m*vf^2 - 1/2*m*vi^2


Work = 1/2*m*(vf^2 - vi^2)





Plug and chug





Anytime you need to find work, just remember it is proportional to the change in energy of a system. If a system does work it will experience a net decrease in energy. If a system has work done to it, it will eperience a net increase in energy.

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