Homework Help: Forces with pulleys

1. Sep 19, 2006

rwofford

so i have this problem with a block sitting on a horizontal surface and this block(m1) has the weight of 420 N. This block is connected by a string to a pulley and then connects to another block(m2) that is hanging from the pulley. The weight of the hanging block is 190 N. Ignore all frictional effects, and assume the pulley to be massless. I have to find the acceleration adn tension.

For this problem i know the free body diagrams..and i also know that the tension asn acceleration will be the same for both blocks. I have tried solving using the net forces but cant come up with an answer...

I have used:

sumF(m1)=Fn+Ft-Fg
sumF=ma
so: Fn+Ft-Fg=ma

sumF(m2)=Ft
sumF=ma
so: Ft=ma

2. Sep 19, 2006

rwofford

3. Sep 19, 2006

rwofford

...hello???

4. Sep 19, 2006

Staff: Mentor

Realize that you can't just add horizontal and vertical forces (like Fn and Ft on m1). Treat horizontal and vertical components separately.

m1 accelerates horizontally, so analyze the horizontal forces acting on m1. Similarly, m2 accelerates vertically, so analyze the vertical forces acting on m2.