*Pulleys introduce a possible source of error because of their possible friction. Given that they are a source of error, why are the pulleys used at all?*To determine the force acting on each mass it was assumed that g=9.80m/sec2. The value of g at the place where the experiment is performed may be slightly different from that value. State what effect (if any) it would have on the percentage error calculated for the comparisons. To test your answer to the question, leave g as a symbol in the calculation of the percentafe error.