Question

In a race, a 54 kg athlete runs from rest to a speed of 11 m/s on a flat surface. The athlete's body has an efficiency of 85% during the run. How much input energy did the athlete provide?

a. 5440 J
b. 4500 J
c. 6300 J
d. 7200 J

Answer 1

The input energy provided by the athlete is 2800 J

Step-by-step explanation:

To calculate the input energy provided by the athlete, we need to find the work done. The work done is equal to the change in kinetic energy of the athlete. The formula for kinetic energy is K.E. = 0.5 * mass * (speed)^2.

First, we find the initial kinetic energy by plugging in the mass (54 kg) and initial speed (0 m/s) into the formula. This gives us an initial kinetic energy of 0 J.

Next, we find the final kinetic energy by plugging in the mass (54 kg) and final speed (11 m/s) into the formula. This gives us a final kinetic energy of 3267 J.

Finally, we find the input energy provided by multiplying the final kinetic energy by the efficiency percentage (0.85). This gives us an input energy of 2777.95 J. Rounded to the nearest hundred, the answer is 2800 J, which corresponds to option (d).