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help with physics question please!!!

Hi guys, realised there wasn't a physics thread...Can anyone help me with part C of this question???A Car of Mass 800kg is accelerated from rest to 18ms in 12 seca) calculate size of resultant force on carb) calculate how far the car travels in 12secc) at the end of the 12seconds the brakes are operated and the car comes to rest in a distance of 50mcalculate average frictional force acting on carPLZZ HELP
Using energy conservation:
Initial kinetic's car energy (before brakes are used) = 1/2mv^2 = 129600J
Energy lost by friction or work done by frictional force = Fxd
These two quantities must be equal so:
F = 129600/50 = 2592N.

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