A100 kg roller coaster car is located at the top of a hill where the height is 20 m. what is the velocity when it reaches the bottom of the hill? 5.5 m/s 11.2 m/s 16.7 m/s 19.8 m/s

19.8 m/s

Explanation:

Assuming the car starts from rest, initially when it is at the top of the hill all the mechanical energy of the car is just potential energy, given by:

where

m = 100 kg is the mass

g = 9.8 m/s^2 is the gravitational acceleration

h = 20 m is the height

Substituting,

At the bottom of the hill, all this energy has been converted into kinetic energy (because energy cannot be created or destroyed, but only transformed). Therefore, the kinetic energy of the car is:

where

m = 100 kg is the mass of the car

v is the speed of the car at the bottom of the hill

Re-arranging this equation, we can find the value of v:

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

the answer is 12 as i may remember

: )