- #1

- 40

- 0

## Homework Statement

In the figure here three ballot boxes are connected by cords, one of which wraps over a pulley having negligible friction on its axle and negligible mass. The masses are m1 = 28 kg, m2 = 45 kg, and m3 = 12 kg. When the assembly is released from rest, (a) what is the tension in the cord connecting 2 and 3, and (b) how far does 1 move in the first 0.300 s (assuming it does not reach the pulley)?

## Homework Equations

F= ma

d= vit+1/2at^2

## The Attempt at a Solution

first I got Ft = m1a

Ft - (m2g+m3g) = (m2+m3)a

subtracted those 2 equations and got

-(m2g+m3g)=-(m2+m3)a-m1a

solved for a,

a = (m2g+m3g)/(m2+m3+m1)

a = 6.57176 m/s^2

I did b correctly using the kinematics equation but didn't get A correct.

I thought tension in string is equal for all parts so i did Ft = ma = 184.0 N, but that's wrong.

Is there a connection between block 2 and 3 that I'm missing?

The figure is in the attatchments