MHB Decrease in Potential Energy of a Sliding Tile

[Shah 72]

A tile of mass 1.2 kg slides 3m down a roof that makes an angle of 35 degree to the horizontal. Find the decrease in potential energy.
Iam getting the ans 24.8J
PE = mgh= 1.2× 12 sin 35 ×3
The ans in the textbook is 20.6J

 

[topsquark]

You have the right idea but something went wrong.

Your mistake: PE = mgh = 1.2 x 10 x (3 x sin(35)). Where did you get the 12 from?

PE = mgh = 1.2 x 10 x (3 x sin(35)) = 20.6 J.

(You have to use a Scientific calculator anyway, so I don't understand why you would be told to use g = 10 m/s^2 instead of 9.8 m/s^2. I think it's silly!)

-Dan

 

[Shah 72]

You have the right idea but something went wrong.

Your mistake: PE = mgh = 1.2 x 10 x (3 x sin(35)). Where did you get the 12 from?

PE = mgh = 1.2 x 10 x (3 x sin(35)) = 20.6 J.

(You have to use a Scientific calculator anyway, so I don't understand why you would be told to use g = 10 m/s^2 instead of 9.8 m/s^2. I think it's silly!)

-Dan

Thank you!