physics
posted by melad .
A 10.0kg block is at rest on a horizontal floor. If you push horizontally on the 10.0kg block with a force of 20.0 N, it just starts to move.
(a) What is the coefficient of static friction?
b) A 12.0kg block is stacked on top of the 10.0kg block. What is the magnitude F of the force, acting horizontally on the 10.0kg block as before, that is required to make the two blocks start to move?

Fb = 10kg * 9.8 = 98N = Force of block.
Fb = Fv = 98N,
a. Fh  u*Fv = 0,
20  98u = 0,
98u = 20,
u = 20 / 98 = 0.20.
b. Fb = (10 + 12)kg * 9.8 = 215.6N.
= Force of blocks.
Fv = Fb = 215.6N.
Fh  u*Fv = 0,
Fh = u*Fv = 0.2 * 215.6 = 43.1N = Force required to move the blocks.