Finding Acceleration on an Inclined Plane: A Simple Homework Problem

[Jake4]

Homework Statement

I truthfully don't know what I'm doing incorrectly with this one, it seems VERY straightforward.

A block is released from rest at the top of an inclined plane and moves 3.2 m within 5.1 seconds. The inclined plane makes a 36 degree angle with the horizontal. What is the magnitude of acceleration for the block?

Homework Equations

F=ma

The Attempt at a Solution

I essentially thought this was very straightforward. Set up the mg vector and then simply solve for the side of the plane itself. I tried to do this and it was incorrect. I feel, however, that I'm missing something major here, because I don't see where I use the displacement and time in this. Also the next question is asking for the coefficient of friction.

I'm understanding and plowing through most of these questions, but every once in a while, I get a curve ball that just throws me off.


thanks for the help!

 

[Doc Al]

You need to solve for the acceleration using the distance & time data given (and some kinematics formulas). You cannot assume that gravity is the only force acting. (Friction is acting, too.)

 

[Jake4]

ahhh! totally makes sense now. I swear, when I get in vector mode, I forget about normal kinematics...

thanks so much!