Finding the Correct Force for Acceleration in Kinetics of Translation

[tjohnbridge]

Homework Statement

A 200kg body is supported by wheels @ B to roll freely w/o friction & by a sled @ A with which uk = 0.5. Compute the value of P to cause an acceleration of 0.02g. (g=9.8m/s^2)

NOTE: Image not drawn to scale.
http://www.geocities.com/timothybridge/kinOftrans.JPG

Homework Equations

Efx=max

Efy=0

Emcg=0

Fa=uNa

The Attempt at a Solution

P-Fa=200(0.02)(9.8)

Na+Nb=1960

Nb(1.5)-Na(1.5)+P(1.2)-Fa(1.8)=0

Fa=0.5Na

solving 4 equations simultaneously,

P=491.78N
Na=905N
Nb=1055N

My professor said the answer should be around P=2350N

Can someone identify what's wrong with my solution?

 

[Pyrrhus]

Recheck your third and first equation.