In 1964, after the 1250-kg jet-powered car Spirit of America lost its parachute

Question

In 1964, after the 1250-kg jet-powered car Spirit of America lost its parachute and went out of control during a run at Bonneville Salt Flats, Utah, it left skid marks about 8 km long. (This earned a place in the Guinness Book of World Records for longest skid marks.)

(a) If the car was moving initially at a speed of about 927 km/h, and was still going at about 298 km/h when it crashed into a brine pond, estimate the coefficient of kinetic friction ? k.

(b) What was the kinetic energy of the car 33 s after the skid began?

Explanation / Answer

here ,

vi = 927 km/h = 257.5 m/s

vf = 298 km/h = 82.8 m/s

Now , Using third equation of motion

vf^2 - vi^2 = 2*a*d

82.8^2 - 257.5^2 = 2*8000*a

a = -3.72 m/s^2

Now, as a = -uk*g

-3.72 = -9.8 * uk

uk = 0.379

the coeffieceint of kinetic friction is 0.379

b)

Now , after 33 s

vf = 257.5 - 3.72 * 33

vf = 134.9 m/s

Kinetic energy = 0.5 * 1250 * 134.9^2

Kinetic energy =1.137 *10^7 J

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