Question

The motion of roller coasters depends upon the conversion of potential and kinetic energy. A 100-kg car starts from rest at the top of a hill with a height of 50 m. Which of the following is this car's kinetic energy at the bottom of the hill? 150 J 5000 J 49,000 J 98,000 J

Answer 1

Answer:

The kinetic energy will be 49000[J]

Explanation:

This problem is the common use of energy conservation when the body is at the top at the point where its elevation is the highest (usually the lowest point is taken as the reference level) at that point the body will have the highest potential energy, then as the body descends its potential energy decreases but its kinetic energy begins to increase. By the time the body reaches the lowest point or reference point, its potential energy will be zero, but its maximum kinetic energy, as all potential energy has become kinetic energy.

Therefore:

$Ep=m*g*h\\where\\m =100 [kg]\\g= 9.81 [m/s^2] gravity\\h = 50 [m]\\\\Ep= 100*9.81*50\\Ep=49000 [J]$

This energy will be transformed into kinetic energy at the bottom of the hill.