Question

A car starts motion from rest with speed of 20m/s calculate acceleration after 4 seconds.
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Answer 1

Answer:

since the car is at rest, therefore

initial velocity (u) = 0m/s

final velocity (v) = 20m/s

time (t) = 4s

Therefore, acceleration = (v-u) /t

=(20-0) /4 m/s².

=20/4 m/s²

= 5m/s².

Therefore, the acceleration produced is 5m/s²

Explanation:

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Answer 2

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Acceleration is the rate of change of velocity of a body. It is defined by the expression :

$\bigstar \: a = \frac{v - u}{t}$

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In this question we have been given a body which starts from rest and moves with a velocity of 20m/s. Acceleration of body is not known. We have to find acceleration of body after it's journey of 4 seconds. .

Important keywords :

• Final velocity of car = 20m/s
• Initial velocity = 0 (since it starts from rest)
• Acceleration = a = ?
• In time = 4s.

After inputting the known values in expression of acceleration we get :

$\bigstar \: a = \frac{v - u}{t}$

$\mapsto \: a = \frac{20 - 0}{4}$

$\mapsto \: a = \frac{20}{4}$

$\mapsto \: a = \cancel \frac{20}{4}$

$\mapsto \: a = 5$

Therefore the acceleration of car after 4seconds of journey is 5m/s^2.

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BY SCIVIBHANSHU

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