Question

your instructor challenges you and your friend to pull on the ends of a horizontal rope attached to a pair of scales in a tug-of-war, but in such a way that the scale readings on the scales are different. can this be done? explain.

Answer 1

If the scale readings are different then there will be a net force on the person attached to the scales:

Consider any point on the rope - if the forces in each direction are the same there is no acceleration of the rope

F = Δm * a for any portion of the rope with mass Δm

If any portion of the rope is accelerated, the person attached to the rope must be accelerated