Question

A roller coaster starts from rest at the top ofan 18m hill.

Answer 1

Answer:

12.65 m/s

Explanation:

When friction is ignored, if the car travels from 18m hill to the bottom of the hill, afterwards it travels up to a 10m hill, then overall it has traveled a distance of 18 - 10  = 8 m vertically.

If the car starts from rest, then its potential energy is converted to kinetic energy:

$E_p = E_k$

$mgh = mv^2/2$

where m is the car mass and h is the vertical distance traveled, v is the car velocity at 10m hill

Let g = 10m/s^2. We can cancel m from both sides of the equation:

$gh = v^2/2$

$v^2 = 2gh = 2*10*8 = 160$

$v^2 = 160$

$v = \sqrt{160} = 12.65 m/s$