What is the kinetic energy of the skater 45.0 kg skater is skating down a hill on roller blades at a speed of 10.0 ms?

The kinetic energy (KE) of an object can be calculated using the formula ( KE = \frac{1}{2}mv^2 ), where ( m ) is the mass and ( v ) is the velocity. For a 45.0 kg skater moving at a speed of 10.0 m/s, the kinetic energy would be ( KE = \frac{1}{2} \times 45.0 , \text{kg} \times (10.0 , \text{m/s})^2 = 2250 , \text{J} ). Thus, the skater's kinetic energy is 2250 joules.