Question

a body moving along a straight line at 20m/s undergoes acceleration of 4m/s². after 2 second what will be its speed? also find the displacement.

Answer 1

u = 20 m/s

a = 4 m/s²

t = 2 sec

v = ?

v = u + at

v = 20 +4 x 2

v = 28 m/s

s = v² - u²/ 2a = 28² - 20² / 2 x 2 = 784 - 400/4 = 384/4 = 96 m

Answer 2

Concept:

The kinematical equation which is applied to find the speed and displacement of the body is - v = u + at and s = v² - u²/ 2a.

Given:

Velocity, u = 20m/s

acceleration = 4m/s²

time = 2secs

Find:

We need to determine the speed and displacement of the body.

Solution:

If other information is available, a set of three equations known as the kinematic equations can be used to forecast unknown information about an object's motion.

We have the first kinematical equation as,

v = u + at where v = speed, u = velocity, a = acceleration and t = time

It has been given to us that the velocity is 20m/s, acceleration is 4m/s² and time is 2 secs.

Therefore, speed becomes - v = u + at

v = 20 + 4(2)

v = 20 + 8

v = 28 m/s

We know, v² = u² + 2as

s = v² - u²/ 2a

s = (28)² - (20)² / 2(4)

s = 384 / 8

s = 48m

Thus, the speed and displacement of the body are 28m/s and 48m respectively.

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