Calculating Efficiency of an Inclined Plane

[Jonathan Teas]

Homework Statement

A washing machine that weighs 1400N must be put into a delivery truck bed that is 1.2 m off the ground. A worker uses a force of 450N to push the machine up a ramp that is 4.3m long. What is the efficiency of the inclined plane?

Homework Equations

e=(MA/IMA)100---- efficiency of a machien in % is = to its mechanical advantage, divided by the ideal mechanical advantage, multiplied by 100.
MA=Fr/Fe---- mechanical advantage=the resistance of force divided by the effort force.
IMA=De/Dr----the ideal mechanical advantage of an ideal machien is=to the displacement of the effort force, divided by the displacement of the load.

The Attempt at a Solution

MA=1400N/450N=3.11N, I think i did that part right.
IMA=1.2m/4.3m=0.28m, I think i did this part wrong.
e=(3.11N/0.28m)100=1110.71joules.

 

[rl.bhat]

Hi Jonathan Teas, welcome to PF.
First of all MA or IMA are pure numbers. No units for them.
Next IMA = Distance traveled by effort/ distance traveled load. = ...?
In Ist or second type of machine IMA cannot be less than one.

 

[Jonathan Teas]

Hi Jonathan Teas, welcome to PF.
First of all MA or IMA are pure numbers. No units for them.
Next IMA = Distance traveled by effort/ distance traveled load. = ...?
In Ist or second type of machine IMA cannot be less than one.

If IMA= Distance traveled by effort/ distance traveled load
then IMA= 4.3m/1.2m=3.58 then no unit?
so the answer is 3.11no unit again/3.58=(0.87)100=87%
Thank you very much.