A car accelerates uniformly at 3 m/s2 from rest to a speed of P in 10 s. It travels at speed P constantly for 16 s and is brought to rest with uniform deceleration in 6 s.
(a) Calculate speed P and hence find the total distance travel by the car.
(b) The mass of the car is 1500 kg. Calculate the force needed to bring the car to a stop.
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Answer:
(a) v = u + at
speed P = 0 + 3 * 10
speed P = 30 m/s
total distance = area under graph
= (½ * 10 * 30) + (30 * 16) + ( ½ * 30 * 6)
= 150 + 480 + 90
= 720 m
(b) deceleration = 30 / 6 = 5 m/s2
Hence, force required to stop the car = ma
= 1500 * 5
= 7500 N
