How Far Does a Boulder Travel Rolling Downhill with Constant Acceleration?

[Doraneli]

1. A boulder initially at rest rolls down a hill with an acceleration of 3.69m/s^2. If it accelerates for 7.72 seconds, how far will it move?


2. d=v0(initial velocity)t+.5at^2



3. d=(0)(7.72)+.5(-9.8)(3.27)^2
-39.24+-52.4
-91.64m

 

[HallsofIvy]

1. A boulder initially at rest rolls down a hill with an acceleration of 3.69m/s^2. If it accelerates for 7.72 seconds, how far will it move?


2. d=v0(initial velocity)t+.5at^2



3. d=(0)(7.72)+.5(-9.8)(3.27)^2

Why is t= 7.72 in the first term and 3.27 in the second?

-39.24+-52.4

Where did the "-39.24" come from? And why the "+-" for the second term?

-91.64m

 

[Sixty3]

You are using the correct equation, but your values for 'a' and 't' are wrong.
The acceleration of the ball is given to you in the question, so you don't need to use 9.81m/s². And also the time stated in the question is 7.72s.