Work question?

Question

An object of mass 10kg whose initial speed is 2m/s is accelerated until it achieves a final speed of 9m/s.

a)How much work was done on this object?

W = FDcos0

so its W = F * displacement

im not given the displacement so how am i suppose to figure this one out?

Answer 1

you can do it via kinetic energy, since work = energy

KE =  Ã‚½mV²

ΔKE =  Ã‚½mV₁² -  Ã‚½mV₂²

ΔKE =  Ã‚½m(V₁² - V₂²)

ΔKE =  Ã‚½10(9² - 2²)

ΔKE =  5(81 - 4) = 5*77 = 385 J

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