Explain me this concept (Laws of Motion)

[snshusat161]

Two blocks placed one on top of the other are lying on a horizontal smooth surface. The coefficient of friction between the blocks is $$\mu$$.

Case 1: Horizontal force F is applied to the lower block (Fig. 14).

[PLAIN]http://www.monbattle.com/1.jpg[/CENTER]

Please help me to find out how they have got those equations. I'm trying to find it from past several hours but couldn't got any hint.​

 

[tiny-tim]

Hi snshusat161!

(your link isn't working … it's http://www.monbattle.com/1.jpg" )

You need to do good ol' Newton's second law (F = ma) twice, once for each block.

What equations do you get? ​