Solving a Pulley Problem: Finding Rope Tension

[Oliviam12]

I have a question on a pulley problem; the problem looks like this:

M (10) ...O
------------|...
xxxxxxxxxxxx|...
xxxxxxxxxxxx|m (2.5)
xxxxxxxxxxxx|...
With the: O being a frictionless pulley
- being solid ground
. Being a rope
M a mass of 10 kg
m a mass of 2.5 kg

I need to find the tension in the rope.

I have found the acceleration of the masses by:
FM=ma
=10*0
=0 N

Fm=2.5 *9.81
Fm= 24.525 N

A=F/M
A=(24.525 N)/ (10+2.5)
A= 1.962 m/s^2

I know I need to use the equation T= m(g+a) or T=m(g-a) but, I am not sure which one or what mass I am supposed to use. (maybe 2.5 kg?)

 

[learningphysics]

I don't understand these parts:

"FM=ma
=10*0
=0 N"

"Fm=2.5 *9.81
Fm= 24.525 N"

24.525 is the force of gravity on m... is that what you meant here?

You have the right acceleration... The top mass has only one force acting on it.. tension... so Tension = ma