A car accelerates from rest to u m/s. The en | vedclass

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(B) According to the work-energy theorem,the work done (energy spent) is equal to the change in kinetic energy.For the first process (from rest to $u

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$3$

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(B) According to the work-energy theorem,the work done (energy spent) is equal to the change in kinetic energy.For the first process (from rest to $u \ m/s$):$E_1 = \frac{1}{2} m u^2 - 0 = \frac{1}{2} m u^2 = E$For the second process (from $u \ m/s$ to $2u \ m/s$):$E_2 = \frac{1}{2} m (2u)^2 - \frac{1}{2} m u^2$$E_2 = \frac{1}{2} m (4u^2) - \frac{1}{2} m u^2 = 2 m u^2 - 0.5 m u^2 = 1.5 m u^2 = 3 \left( \frac{1}{2} m u^2 \right)$Since $E = \frac{1}{2} m u^2$,we have $E_2 = 3E$.Comparing this with $nE$,we get $n = 3$.

$A$ car accelerates from rest to $u \ m/s$. The energy spent in this process is $E \ J$. The energy required to accelerate the car from $u \ m/s$ to $2u \ m/s$ is $nE \ J$. The value of $n$ is ..............

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