Question

A body is moving along a straight line at 20m/s undergoes of 4m/s*s after 2sec speed will be??

Answer 1

Initial velocity = 20 m/s
Acceleration = 4 m/s^2
Time = 2 seconds

So, by the first equation of kinematics
v = u+at
Therefore,
Final velocity (v) = 20+4*2 = 28 m/s
Now, we know that the speed of the body will also 28 m/s since the magnitude of speed and velocity of the same body is same however the velocity gives a well defined direction of the motion of the body.

So, the speed of the body along the straight line after 2 seconds will be 28 m/s.

Answer 2

✬ Final Speed = 28 m/s ✬

Explanation:

Given:

• Uniform speed (u) of body is 20 m/s.
• Acceleration (a) produced by body is 4 m/s².
• Time (t) is 2 seconds

To Find:

• What will be the final speed of body?

Formula to be used:

• v = u + at

Solution: Using the first equation of motion

$\implies{\rm }$ v = u + at

$\implies{\rm }$ v = 20 + 4 $\times$ 2

$\implies{\rm }$ v = 20 + 8

$\implies{\rm }$ v = 28 m/s

Hence, the final speed of body will be 28 m/s.

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Another Method

As we know that

★ Acceleration = ( Final velocity – Initial Velocity / Time ) ★

$\implies{\rm }$ a = ( v – u/t )

$\implies{\rm }$ 4 = ( v – 20/2 )

$\implies{\rm }$ 4 $\times$ 2 = v – 20

$\implies{\rm }$ 8 = v – 20

$\implies{\rm }$ 8 + 20 = v

$\implies{\rm }$ 28 m/s = v

Hence, the final speed of body will be 28 m/s.