A skier of mass 50 kg is moving at speed 10 m/s at point P₁ down a ski slope with negligible friction.What is the skier's kinetic energy when she is at point P₂,20 m below P₁? A)2500 J B)9800 J C)12300 J D)13100 J E)15000 J

Question

Quizplus · Accepted Answer

The skier's potential energy at point P₁ can be calculated as follows: PE = mgh = (50 kg)(9.8 m/s^2)(0 m) = 0 J where m is the mass of the skier, g is the acceleration due to gravity (9.8 m/s^2), and h is the height above the reference point (0 m). The skier's potential energy at point P₂ can also be calculated: PE = mgh = (50 kg)(9.8 m/s^2)(20 m) = 9800 J where m, g, and h have the same meanings as before, but h is now 20 m. Since there is negligible friction, the skier's total energy is conserved (i.e., the sum of kinetic energy and potential energy is constant). Therefore, the skier's kinetic energy at point P₂ can be calculated as follows: KE = total energy - PE KE = 9800 J - 0 J = 9800 J Therefore, the skier's kinetic energy at point P₂ is 9800 J, which corresponds to choice C.

A Skier of Mass 50 Kg Is Moving at Speed