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Very EASY math acceleration problem! help!?
A car traveling 56.0 km/h is 22.8 m from a barrier when the driver slams on the brakes. The car hits the barrier 2.22 s later.
(a) What was the car's constant deceleration just before impact (assume the car is traveling in the positive direction)?
____ m/s2
(b) How fast was the car traveling just before impact?
___ m/s
1 Answer
- Anonymous1 decade agoFavorite Answer
56.0 km / hr = (56 / 3.6) m / sec.
(a)
s = ut + at^2 / 2
a = 2(s - ut) / t^2
= 2(22.8 - 56 * 2.22 / 3.6) / 2.22^2
= - 4.76 m/s^2.
Deceleration is 4.76 m/s^2.
(b)
s = t(u + v) / 2
v = 2s / t - u
= 2 * 22.8 / 2.22 - 56 / 3.6
= 4.98 m/s.