Question

A car starts moving along a line, first with acceleration a=5m/s2 starting from rest then uniformly and finally decellerating at the same rate and comes to rest. The total time of motion is 25sec. The average speed during the time is 20m/s. How long does the particle move uniformly?

Answer 1

Case 1

Here,
t=25s
u=0
a=5m/s^2

$a = \frac{v - u}{t}$
$5 = \frac{v - 0}{25}$
$125 = v$
Case 2

v= 125m/s
a=5m/s^2
u=0

$a = \frac{v - u}{t}$
$5 = \frac{125 - 0}{t}$
$5t = 125$
$t = \frac{125}{5}$
$t = 25s$

Answer 2

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