Question

A body moving along a straight line at 20m/s undergoes an
acceleration of -4m/s 2 .
The velocity of the object after 2 seconds will be:
(a) -8m/s
(b) 12m/s
(c) 16m/s
(d) 28m/s

Answer 1

Answer:

Given:

Initial Velocity (u) = 20 m/s

Acceleration (a) = -4m/s²

To Find:

The velocity of the object after 2 seconds

Solution:

We know that,

Law's of Motion

First equation of motion,

$\boxed{\sf v = u +at}$

Given that,

u = 20 m/s

a = -4m/s²

t = 2 s

Therefore,

By substituting the given values in the above equation

We get,

$\sf \implies v = 20+(-4)(2)\;m/s$

$\implies \sf v = 20 + (-8)\;m/s$

$\implies \sf v = 20 -8\;m/s$

$\sf \implies v = 12 \;m/s$

Hence,

The velocity of the object after 2 seconds is 12 m/s

Option (b) is correct

Answer 2

Solution:

We know that,

Law's of Motion

First equation of motion,

V=u+at

Given that,

u = 20 m/s

a = -4m/s²

t = 2 s

Therefore,

By substituting the given values in the above equation

V=20+4*2

V=20+8

V=28m/s

The velocity of the object after 2 seconds is 12m/s

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