# Finding maximum velocity?

shock7221
finding maximum velocity??

A block of mass M = 275.0 g sits on a horizontal tabletop. The coefficients of static and kinetic friction are 0.54 and 0.38, respectively, at the contact surface between table and block. The block is pushed on with a 12.0 N external force at an angle θ below the horizontal.
(a) What angle will lead to the maximum acceleration of the block for a given pushing force?
20.8° above the horizontal

(b) What is the maximum acceleration?
43 m/s^2

those were the answer given. I know how you get the degrees but i am having trouble how to find the maximum acceleration... can you guy help me?

Mentor

Well, if you managed to find the angle, you should have no trouble plugging it into the equation you found for the maximum acceleration...

shock7221

well i did. a=(sin20.8)(9.8)(12)= 41.7 m/s^2.. its close but it is not the right answer.

Mentor

Perhaps you should start with a free body diagram of the forces, and determine the net horizontal force acting. Newton's second law then provided the acceleration.