Homework Help: physics

Posted by april on Saturday, January 31, 2009 at 10:52am.

a 200 kg block was moved along an inclined plane to a height of 10m. during this process 3000J of energy was lost due to friction.

a. calculate the efficiency of the inclined plane.

b. what would the efficiency of the simple machine be if the incline were frictionless?

c. how would the efficiency of the inclined plane change (decrease or increase or no change) if the incline were longer with no change in height? Hint: consider change of work due to friction.

please explain more than just giving me an equation.

physics - drwls, Saturday, January 31, 2009 at 11:48am
a) The efficiency is the increase in potential energy that results (Weight x height change), divided by the work that had to be done.

b) 100%

c) With a less steep ramp angle, the friction force goes up while the distance needed to push the block also goes up. The work done against gravity strays the same. This increases the work required. What does that do to the effciciency ratio (P.E. change)/Work ?
physics - april, Saturday, January 31, 2009 at 12:06pm
a. how do i encorporate the 3000J of lost energy?
physics - drwls, Saturday, January 31, 2009 at 2:33pm
Add the friction work to the work done against gravity, M g H, to get the total work required. (in part a)
physics - april, Saturday, January 31, 2009 at 3:11pm
i still dont understand how you put that into the formula

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