Calculating Mass and Force: A Pulley Problem

[redlightgreen]

Homework Statement

The 100 kg blcok in the figure takes 5.40 s to reach the floor after being released from rest. What is the mass of the block on the left?

Homework Equations

F=ma
s_f=s_i + (1/2)(a)(delta t)

The Attempt at a Solution

I know to find acceleration you use
s_f=s_i + (1/2)(a)(delta t)
0=1+(1/2)(a)(5.4)
a = 0.0686 m/s²

and then the F=ma to find the force on the block of known mass.
F=(100 kg)(0.0686)
F=6.86

but from this I am not sure how to determine the mass of the block on the left?

 

[tiny-tim]

Welcome to PF!

a = 0.0686 m/s²

and then the F=ma to find the force on the block of known mass.
F=(100 kg)(0.0686)
F=6.86

but from this I am not sure how to determine the mass of the block on the left?

Hi redlightgreen! Welcome to PF!

Find the tension, T, and then use the fact that the block on the left has the same acceleration (in the opposite direction, of course).

 

[redlightgreen]

oh okay! thank you so much.
i've got it now!