A body is moving with a speed of 20m/s if the motion is uniform, what is its velocity after 10 sec

A body was moving with a constant velocity of 20 m/s. When an external force is applied, it produces an uniform acceleration of 4 m/s2. What is the time taken to reach 80 m/s and also find the velocity at half of that time? [3 MARKS]

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$u=20m/s,v=80m/s,a=4m/s^2$

Using Equation, $v=u+at$
$80=20+(4\times t)$
$4t=60$
$t=15s$ Therefore, time taken to reach 80m/s is 15 s. Velocity at 7.5 s

$v=20+4\times 7.5=50m/s$