- #1

Nanu Nana

- 95

- 5

## Homework Statement

A sled starts from rest and slides down an inclined plane with constant acceleration. In three seconds, it has traveled 9m. How long does it take to reach a velocity of 24m / s?

## Homework Equations

d = vi * t + ½ * a * t^2, vi = 0[/B]

vf = vi + a * t, vi = 0

## The Attempt at a Solution

d = vi * t + ½ * a * t^2, vi = 0

9 = ½ * a * 3^2

a = 18 ÷ 9 = 2 m/s^2

To determine the time, we need to determine the sled’s acceleration.

vf = vi + a * t, vi = 0

24 = 2 * t

t = 12 seconds.[/B]

I solved this problem with help of someone else . The thing I don't understand is why can't we use 9,81 m/s2 for acceleration . Because the sled is sliding down . Doesn't it has to do with gravity ?