Find the time taken by a car to travel 5.4 km moving with 20m/s.
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Answer:
If questions be like “velocity, distance”, you should always try to counter with
v^2 - u^2 = 2as
If possible.
Here, it is. A car moving at 20m/s is to be stopped in 40m of distance travelled. So:
0^2 - 20^2 = 2a(40)
-400/2*40 = a
-5m/s^2 = a
As we've found the retardation, we can easily use
v = u + at
0 = 20 - 5t
4 = t
So, we need 4s to satisfy the given conditions spot on.
PS
Funny that some people try to use
s = ut + at^2/2
After finding the accel, which only overcomplicates things.
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Answer:
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Explanation:
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