Question

A roller coaster accelerates at a rate of - 3 m/s ^ 2 from 25 m/s at the bottom of a hill to 10 m/s s at the top How long does it take the coaster to reach the top of the hill ?

Answer 1

5 seconds

Step-by-step explanation:

Acceleration,
`a=\frac {v-u}{t}`

Where v and u are the final and initial velocities of the roller coaster respectively, t is the time taken for the coaster to reach the top of the hill.

Making t the subject then

`t=\frac {v-u}{a}`

Substituting -3 m/s2 for a since it decelerates, 25 m/s for u, then 10 m/s for v then

`t=\frac {10-25}{-3}=5 s`