- #1

hazybluesky

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## Homework Statement

Barry carries his tray of food to his favorite cafeteria table for lunch. The 0.5-m-long tray has a mass of 0.2 kg and holds a 0.4-kg plate of food 0.2 m from the right edge. Barry holds the tray by the left edge with one hand, using his thumb as the fulcrum, and pushes up 0.1 m from the fulcrum with his finger tips. How much upward force must his finger tips exert to keep the tray level?

g= 10 m/s^2

## Homework Equations

Torque= Perpendicular Force x Lever Arm (T=Fxd)

Fw=mg

## The Attempt at a Solution

Torque of tray...

Fw=mg

Fw= 0.2 * 10

Fw=2 N

d= length of tray? or 0.5 m? I'm not sure

T=Fxd

T=2*0.5

T= 1 <<<<<Torque of tray

Torque of plate...

Fw=mg

Fw= 0.4 * 10

Fw= 4 N

d= I have absolutely no idea!

T= 4 * ?? <<< Torque of plate

Then would you add the torque of the plate and tray together?

And then find the force using the that total torque? But what d value would you use?

Please, help me

Thank you!

-Ashley