How Fast Does a Boulder Roll Downhill After a Tremor?

[etSahcs12]

Homework Statement

A slight Earth tremor causes a large boulder to break free and start rolling down the mountainside with a constant acceleration of 5.2 m/s^2. What is the boulder's velocity after 5.0s.

Homework Equations

I used: v2 = v1 + a x Δt

The Attempt at a Solution

v1 = 0 [because it started to break free]
a = -5.2m/s^2 [because of the sign convention down]
Δt = 5.0s
v2 = ? [because it is finding velocity after 5.0s]

ok it was v2 = 0 + (-5.2m/s^2)(5.0s)
v2 = -26 m/s

Am I correct or have a done a simple mistake that would impact my answer?

 

[mgb_phys]

Correct

 

[m2003]

Your solution is correct. The boulder's velocity after 5.0s would be -26 m/s, assuming it started from rest. It is important to pay attention to the sign convention and make sure it is consistent throughout the problem. In this case, the negative sign for acceleration indicates that the boulder is moving in the downward direction.