Question

a car moving with a speed of 60m/s comes to rest after 8 seconds finds its acceleration

Answer 1

Answer:

-7.5 m/s²

Explanation:

As per the provided information in the given question, we have :

• Initial velocity (u) = 60 m/s
• Final velocity (v) = 0 (As it comes to rest)
• Time taken (t) = 8 seconds

We are asked to calculate acceleration.

By using the first equation of motion :

⇒ v = u + at

• v denotes final velocity
• u denotes initial velocity
• a denotes acceleration
• t denotes time

⇒ 0 = 60 + 8a

⇒ 0 - 60 = 8a

⇒ -60 = 8a

⇒ -60 ÷ 8 = a

⇒ -7.5 m/s² = a

∴ Acceleration of the car is -7.5 m/s².

(Negative sign denotes that the speed is decreasing.)

$\rule{200}2$

More Information :

• Acceleration is the rate of change in velocity with time.
• It is a vector quantity.
• Its SI unit is m/s².
• Negative acceleration is called retardation.

If we've been given time, initial velocity and final velocity, then we can find acceleration in two ways :

By using acceleration formula :

$\longmapsto \rm { a = \dfrac{v-u}{t} }$

By using first equation of motion :

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

Answer 2

Answer:-

• initial velocity=u=60m/s
• Final velocity=v=0m/s
• Time=t=8s

We know that

$\boxed{\sf Acceleration=\dfrac{v-u}{t}}$

$\\ \sf\longmapsto Acceleration=\dfrac{0-60}{8}$

$\\ \sf\longmapsto Acceleration=\dfrac{-60}{8}$

$\\ \sf\longmapsto Acceleration=-7.5m/s^2$