Question

A young girl is riding a bicycle that has a total mass (including the kid) of 21 kg. the girl is moving at 4.23 m/s on a flat road when she suddenly slams on the brakes and skids to a stop in 13.7 meters. how many joules of work was done on the bike girl?

Answer 1

The work done on the bike and the girl is 191.64915 J.

Step-by-step explanation:

To calculate the work done on the bike and the girl, we need to use the work-energy principle. According to the principle, the work done on an object is equal to the change in its kinetic energy. In this case, the work done on the girl and the bicycle is equal to the change in their kinetic energy.

Given that the girl's mass is 21 kg and her initial velocity is 4.23 m/s, we can calculate her initial kinetic energy. Using the formula for kinetic energy, KE = 1/2 * mass * velocity^2, the initial kinetic energy is calculated as (1/2) * 21 kg * (4.23 m/s)^2 = 191.64915 J.

When the girl slams on the brakes and comes to a stop, her final velocity is 0 m/s. Therefore, her final kinetic energy is also 0 J. The work done on the girl and the bicycle is the difference between the initial and final kinetic energies, which is 191.64915 J - 0 J = 191.64915 J.