Afarmer tosses a rope over a beam at the top of a barn. he ties one end of the rope to a bale of hay. he then raises the bale up to the barn loft by pulling down on the loose end of the rope. why does the input force have to be greater than the force needed to lift the bale? a. friction increases the effect of the input force. b. friction eliminates the work input. c. friction reduces the work input.

Option A, Friction increases the effect of the input force.

Explanation:

The beam tied to the top of barn is not a friction less  lever as are the pulleys.

Due to this some frictional force will arise at the point of contact of rope and the beam.

Now in order to lift the bale of hay , a person pulling the rope has to apply force greater than the weight of hay in order to overcome the frictional forces arising due to beam.

Therefore the   input force have to be greater than the force needed to lift the bale

Hence, option A is correct

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