Question

C: Calculate the kinetic energy of a car with a mass of 1563 kilograms that is traveling at 42 kilometers per hour.

Answer 1

Hello!

C. KE ≈ 9120.105 J

D. m = 151.45 kg

Question C:

Calculate kinetic energy using the formula:

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

Substitute in the given mass. We have to convert kilometers to meters in order to solve.

$\frac{42km}{1hr} * \frac{1hr}{3600sec} *\frac{1000m}{1km} = 11.67 m/s$

Use the equation above:

KE = 1/2(1563)(11.67)

KE ≈ 9120.105 J

Question D:

Plug in the given Kinetic Energy and velocity to solve. Convert kilometers/hour to meters/second:

$\frac{7km}{1hr} * \frac{1hr}{3600sec} *\frac{1000m}{1km} = 1.94 m/s$

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

285 = 1/2(m)(1.94²)

570 = (1.94²)m

151.45kg = m