Mechanics M/j 05

[redscarfz]

I have a problem in question 7 please help me

 

[hassam]

well....use formula power =W.D/T..to find work done by car.....
whenever work is done it increase energy of body whether it be kinetic as in this case or potential......but some enrgy cn also be lost ddue to W.D against friction......we cnt directly use W.D by engine to find distance...since force is variable and also kinematics cnt be applied since acceleration is also variable....
so u need to find w.d against friction since friction is constant......find it using.W.D by engine=Increase in K.E+W.D against resistance..........i hope u understand....it if u need more help on understanding the work-energy theorem then post here......