The Student Room Group

Distance/Time Problem

Problem: A car traveling 55 km/h slows down at a constant 0.50 m/s^2. Calculate (a) the distance the car coasts before it stops, (b) the time it takes to stop, and (c) the distance it travels during the first and fifth seconds.

v(initial) = velocity(initial) = 55km/h = 15.28m/s
v = velocity
a = acceleration = -0.50m/s^2

For (a), I used the equation v^2 = v(initial)^2 + 2a(x - x(initial)) to get the resulting displacement of 230 meters.

For (b), I found the time using the equation v = v(initial) + at, which resulted in 31 seconds.

However, I really have no idea how to approach (c). Any help would be greatly appreciated.
Reply 1
Find where it is after 1s

Find where it is after 4s
Find where it is after 5s
Subtract.
for c) you have u, t and a
for part 2, a is the same, t is still a second but you need a new u which you can work out with v=u+at and plugging in the figures and 4 seconds
Reply 3
s = ut + 1/2 at^2 and plug in t = 1 and t =5
Reply 4
Thanks for the help!

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