Question

question 20
5 points
the kinetic energy of a car is 8×10^6 j as it travels along a horizontal road. how much power is required to stop the car in 10 s?
8×10^6 w
8×10^7 w
8×10^5 w
zero watts
8×10^4 w

Explanation:

Step1: Recall the power formula

Power \( P=\frac{W}{t} \), where \( W \) is work done and \( t \) is time.

Step2: Determine the work done

To stop the car, the work done \( W\) is equal to the initial kinetic energy of the car. Given \( W = 8\times10^{6}\text{ J}\) and \( t=10\text{ s}\).

Step3: Calculate the power

Substitute values into the power formula: \( P=\frac{8\times 10^{6}\text{ J}}{10\text{ s}}=8\times 10^{5}\text{ W}\)

Answer:

\(8\times 10^{5}\text{ W}\) (the third option)