What force is needed to accelerate a 1300 kg car from rest to 20 m/s in 80 m? 10/22/2013 | Sierra from Champion, PA | 2 Answers | 0 Votes Mark favorite Subscribe Comment Comments Numerical answer only in kN to 2 decimal places. 10/22/2013 | Sierra from Champion, PA 3.3 kN 10/22/2013 | Andre W. Comment
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 :) 10/23/2013 | Brad M. Comment
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.) 10/22/2013 | Andre W. Comment
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