Question

A car aquires a velocity of 72km/hr in 10s starting from rest.calculate accelaration and average velocity​

Answer 1

$\large{\underline{\underline{\mathfrak{Answer :}}}}$

Acceleration is 2 m/s²

Average velocity is 10 m/s

$\rule{200}{0.5}$

$\underline{\underline{\mathfrak{Step-By-Step-Explanation :}}}$

Given :

• Initial velocity (u) = 0 m/s
• Final velocity (v) = 72 km/h = 20 m/s
• Time (t) 10 s

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To Find :

• Acceleration
• Average velocity

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Solution :

As we know that :

$\large{\boxed{\sf{a \: = \: \dfrac{v \: - \: u}{t}}}} \\ \\ \implies {\sf{a \: = \: \dfrac{20 \: - \: 0}{10}}} \\ \\ \implies {\sf{a \: = \: \dfrac{20}{10}}} \\ \\ \implies {\sf{a \: = \: 2}} \\ \\ \underline{\sf{\therefore \: Acceleration \: is \: 2 \: ms^{-2}}}$

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Now, use 3rd equation of motion :

$\large{\boxed{\sf{v^2 \: - \: u^2 \: = \: 2as}}} \\ \\ \implies {\sf{20^2 \: - \: 0 \: = \: 2 \: \times \: 2 \: \times \: s}} \\ \\ \implies {\sf{400 \: = \: 4s}} \\ \\ \implies {\sf{s \: = \: \dfrac{400}{4}}} \\ \\ \implies {\sf{s \: = \: 100}} \\ \\ \underline{\sf{\therefore \: Displacement \: is \: 100 \: m}}$

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Now, use formula for average velocity :

$\large{\boxed{\sf{V \: = \: \dfrac{Displacement}{Time}}}} \\ \\ \implies {\sf{V \: = \: \dfrac{100}{10}}} \\ \\ \implies {\sf{V \: = \: 10}} \\ \\ \underline{\sf{\therefore \: Average \: velocity \: is \: 10 \: ms^{-1}}}$