Chapter 9, Problem 53A

A car can go from 0 to 100 km/h in 10 s. If the engine delivered twice the power, how many seconds would it take?

To determine

The time taken by a car to delivered twice the power.

Answer to Problem 53A

  $t=5\sec$

Explanation of Solution

Given:

Time $t_1=10\sec$

Speed increase from $0\text{km}/\text{h}$ to $100\text{km}/\text{h}$

Formula used:

Power delivered by engine is given by,

  $P=\frac{W}{t}$

Where $W=$

  $$ work done, $t=$ time

Calculation:

Initial power is,

  $P_1=\frac{W}{t_1}$

And, $P_2=\frac{W}{t_2}$

Here, the engine delivered twice the power $P_2=2P_1$

  $\frac{P_2}{P_1}=\frac{W}{t_2}\times \frac{t_1}{W}$

  $t_2=\frac{10}{2}=5\sec$

Conclusion:

Thus, the time taken by a car is $5\sec$ .