What force is needed to accelerate a 1300 kg car from rest to 20 m/s in 80 m?

Hey Sierra -- ave speed 10m/s travels 80m in 8 sec ... accel is 20/8 = 2.5 m/s/s ...

F=ma ... 1300kg(2.5m/s/s) = 2600N + 650N ~ 3.3kN ... Best wishes :)

What force is needed to accelerate a 1300 kg car from rest to 20 m/s in 80 m?

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Blacksburg, VA

Hey Sierra -- ave speed 10m/s travels 80m in 8 sec ... accel is 20/8 = 2.5 m/s/s ...

F=ma ... 1300kg(2.5m/s/s) = 2600N + 650N ~ 3.3kN ... Best wishes :)

New Wilmington, PA

The work-energy theorem states that the work done by non-conservative forces equals the change of the object's kinetic energy:

W = ΔKE

Now use the definitions of work and KE:

W = F Δx , ΔKE = KE_{f} - KE_{i} = ½m(v_{f}^{2}-v_{i}^{2})

so that

F Δx = ½m(v_{f}^{2}-v_{i}^{2})

F = ½(1300 kg) ((20m/s)²-0)/(80m) = 3,300 N

(I'm assuming 2 significant digits, though it could be just 1.)

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