ICSE Class 10 Physics 2023 Solved Paper

A car of mass $120 {\kg}$ is moving at a speed 18 ${\km} \/ {\h}$ and it accelerates to attain a speed of $54 {\km} \/ {\h}$ in 5 seconds. Calculate :

Question : 53 of 76

Marks: +1, -0

the work done by the engine.

Solution:

Given :

m=120 {\kg}

\;u=18 {\km} \/ {\h}=18 × \;{1000}/{60 × 60}=5 {\m} \/ {\ s}

\;v=54 {\km} \/ {\h}=54 × \;{1000}/{60 × 60}=15 {\m} \/ {\ s}

By work energy theorem,
Work done = Increase in Kinetic Energy

⇒\; {\W}\;=\;{1}/{2} m v^2-\;{1}/{2} m u^2

⇒\; {\W}\;=\;{1}/{2} m (v^2-u^2)

⇒\; {\W}\;=\;{1}/{2} × 120 × (15^2-5^2)

=60 ×(225-25)

\;=60 × 200

\;=12000 {\J}

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