Energy required to accelerate a car from 10 ,m/s to 20, m/s is how many times energy required to acc

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5.Work, Energy, Power and Collision

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The energy required to accelerate a car from $10 \,m/s$ to $20\, m/s$ is how many times the energy required to accelerate the car from rest to $10\, m/s$

A

Equal

B

$4 $ times

C

$2$ times

D

$3$ times

Solution

(d) Kinetic energy for first condition

=$\frac{1}{2}m\left( {v_2^2 – v_1^2} \right) = \frac{1}{2}m\left( {{{20}^2} – {{10}^2}} \right)$= $150\;mJ$

$K.E.$ for second condition = $\frac{1}{2}m\left( {{{10}^2} – {0^2}} \right) = 50mJ$

$\therefore \frac{{(K.E.)_I}}{{(K.E.)_{II}}} = \frac{{150m}}{{50m}} = 3$

Standard 11

Physics

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