Object sliding down inclined plane

[akatsafa]

An object slides down an inclined plane of angle 30 degrees and of incline length 4m. If the initial speed of the object is 5m/s directed down the incline, what is the speed at the bottom? Neglect friction.

I used Kinitial+Uinitial=Kfinal+Ufinal. I got 2gh+5^2=v^2, but when I solve for v, I get 10.17m/s. What am I doing wrong?

 

[Doc Al]

I used Kinitial+Uinitial=Kfinal+Ufinal. I got 2gh+5^2=v^2, but when I solve for v, I get 10.17m/s. What am I doing wrong?

What did you use for h? h must be the vertical distance the object moves, not the distance along the incline.

 

[akatsafa]

Should I use 4sin30 as my height?

 

[Doc Al]

Should I use 4sin30 as my height?

Yes. That's the height.