- #1

Colt 45 J

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**Problem Statement**

A 50cm by 30cm by 20cm block weighing 150N is to be moved at a constant velocity of .8 m/s on an inclined surface with a friction coefficient of 0.27. (a) Determine the force f that needs to be applied in the horizontal direction. (b) if a .4mm thick oil film with a dynamic viscosity of .012Pa*s is applied between the block and inclined surface, determine the percent reduction in the required force.

**Given:**P=150N V=.8m/s a=0, mu(v)=.012Pa*s mu(f)=.27

**Find**: F(a), F(b), %r

**Diagram:**

http://img18.imageshack.us/img18/7915/fluids275.png [Broken]

**The attempt at a solution**

I solved the F(a) to be 40.5N using statics equations (since there is no acceleration F=ma=0)

When using the equations presented in my text I get:

F=mu(v)*A*V/l

F=.012*(.5*.2)*.8/.0004

F=2.4

F(b)=2.4/cos(20*)

F(b)=2.554N

Thus the percentage would be a ~94% reduction in force, which sounds highly unrealistic and leads me to think I did something wrong...

Some Help?

Thanks, Colt 45 J

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