Question

A body moving along a straight line at 20 m/s undergoes an acceleration of-4 m/s2. After two seconds its speed will be (a) -8 m/s (b) 12 m/s (c) 16 m/s (d) 28 m/s

Answer 1

Answer:

ANSWER IS. (B)

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Answer 2

Explanation:

GIVEN : -

Initial speed , u = 20 m / s

Final speed , v = ?

Acceleration , a = - 4 m / s²

Using First equation of motion , we get ,

$\implies \: v \: = u \: + \: at \\ \\ \\ \implies \: v \: = 20 + ( - 4) \times 2 \\ \\ \implies \: v \: = 20 - 8 \\ \\ \implies \: v \: = 12 \: m {s}^{ - 1}$