A car which was moving at 25m/s comes to rest in how many seconds if it travelled a distance 100m before coming to rest?
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Answer:
The required time taken is 8 sec
Explanation:
Given :
A car which was moving at 25 m/s comes to rest and travelled a distance 100 m before coming to rest.
To find :
the time taken
Solution :
Let t sec be the time taken
Initial velocity, u = 25 m/s
final velocity, v = 0 m/s
distance travelled, s = 100 m
Substituting in v² - u² = 2as,
0² - 25² = 2(a)(100)
-625 = 200a
a = -625/200
a = -3.125
The acceleration is -3.125 m/s²
We know that the acceleration is the rate of change of velocity.
a = (v - u)/t
-3.125 = (0 - 25)/t
-3.125 = -25/t
t = 25/3.125
t = 8
Therefore, the required time taken is 8 sec
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