Determine the gross force needed to bring a car which is traveling at 110 km/hr

Question

Determine the gross force needed to bring a car which is traveling at 110                      

km/hr to a full stop in a distance of 100 m. The mass of the car is 2100 kg.

What happens to the initial kinetic energy, where does it go or to what form of

energy does the kinetic energy convert to?

I know that acceleration is -4.668 m/s as a result of the formula Vf^2=Vi^2 + 2ad, however I do not understand how 0 = 110^2 + 2*a*100 = -4.668. Please explain this and the conversion of KE to work done. Thank you.

Explanation / Answer

v2^2 - v1^2 = 2*a*d

here v2 = 0, V1 = 110*5/18 = 30.56 m/s,d = 100

a = -4.668 m/s^2

Fnet = m*a = -9802.8 N.

this is the force exerted by friction.

here negative work is done by friction. that is why the kinetic energy of the car decreases.

this energy is converted in to heat energy. if the car goes in the night we can see a spark in between tires and road.

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