and a bicycle of total mass 75kg to 20 mph(8.9m*s^-2)...starting from from rest and ignoring friction and wind resistence.... you are supposed to use the kinetic energy equation Ek=1/2*mv^2
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W = ΔKE
= 1/2 * m (vf^2 - vi^2) ---> vi = 0 vf = 20 mph = 8.94 m/s
= 1/2 * 75 * ( 8.94^2 - 0)
= 2997.13 J
= 1/2 * m (vf^2 - vi^2) ---> vi = 0 vf = 20 mph = 8.94 m/s
= 1/2 * 75 * ( 8.94^2 - 0)
= 2997.13 J
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The person and bike will have a kinetic energy of
E = 1/2 m v^2 .
Where did they get this energy from? From you doing work (pushing them to that speed)! So how much work did you do, i.e. how much energy did yo u give to the person+bike? 1/2 m v^2 !
E = 1/2 m v^2 .
Where did they get this energy from? From you doing work (pushing them to that speed)! So how much work did you do, i.e. how much energy did yo u give to the person+bike? 1/2 m v^2 !
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FD = KEf - KEi KEi = 0 because at rest
there fore the energy needed to accellerate the car is the same as the final kinetic energy
KE = 0.5 (75)(8.9)^2 = 2970.375
there fore the energy needed to accellerate the car is the same as the final kinetic energy
KE = 0.5 (75)(8.9)^2 = 2970.375