Question

Using the work energy theorem. What is the velocity of a 850kg car after starting at rest when 13,000J of work is done to it.

Answer 1

When the car starts moving it acquires kinetic energy.

For this problem the formula of kinetic energy is:

$\frac{1}{2}mv^2$

Where m is the mass of the car = 850kg, and v is the speed of the car.

If we consider insignificant the energy lost by friction with soil and air we can propose the following equation:

Applied energy = Kinetic energy acquired by the car.

$13000\ J = \frac{1}{2}mv^2\\\\13000\ J = \frac{1}{2}(850)v^2\\\\\frac{13000(2)}{850} = v^2\\\\v = \sqrt{\frac{13000(2)}{850}}\\\\v = 5.531 m/s$

The velocity is 5.531 m/s