Question

A car travelling at 60 km /h on applying breaks stopped in 10 seconds
..Calculate its acceleration

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Answer 1

Answer:

$\bf {-1.\bar{6} }$ m/s²

Explanation:

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

• Initial velocity (u) = 60 km/h
• Final velocity (v) = 0 (As it stops)
• Time taken (t) = 10 seconds

We are asked to calculate its acceleration.

In order to calculate its acceleration, firstly we need to convert initial velocity in its standard form, that it m/s.

$\longmapsto\bf { u = 60 \; kmh^{-1} }$

• 1 km/h = 5/18 m/s

$\longmapsto\bf { u = \Bigg ( 60 \times \dfrac{5}{18} \Bigg ) \; ms^{-1} }$

$\longmapsto\bf { u = \Bigg ( \dfrac{300}{18} \Bigg ) \; ms^{-1} }$

$\longmapsto\bf { u = 16.\bar{6} \; ms^{-1} }$

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Now, by using the acceleration formula:

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

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

$\longmapsto \rm {a = \dfrac{0-16.\bar{6} }{10} \; ms^{-2} }$

$\longmapsto \rm {a = \dfrac{-16.\bar{6}}{10} \; ms^{-2} }$

$\longmapsto \bf {a = -1.\bar{6} \; ms^{-2} }$

∴ Acceleration of the car is $\bf {-1.\bar{6} }$ m/s².

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More Information:

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