# Lab - Investigation of Pulleys

Topics: Force, Kilogram, Mass Pages: 3 (621 words) Published: November 11, 2008
Equipment: 2 Ring Stands, 1-kg mass, pulley blocks, 2 meter sticks, cross bar, 10-N spring scale, 3-m of string One Pulley LOAD is the weight of the 1-kg mass. LOAD = mg LOAD = (1.002 kg)(9.8 m/s2)

LOAD (L) = 9.8 Newtons LOAD DISTANCE is the height the mass is raised LD = 0.5 meters EFFORT is the force applied to move the load upward at a constant speed. EFFORT (E) = 10 Newtons EFFORT DISTANCE is the length of string pulled ED = 0.51 meters Is L x LD = E x ED? 9.8 x 0.5 = 10 x 0.51 No, Off by 0.2 Is there any advantage in using a pulley like this? Pulling down instead of pulling up The Mechanical Advantage (MA) = LOAD/EFFORT For this Pulley MA = 9.8/10 = 0.98. What about the differences in distances moved? 0.01 meters If the LOAD moves up 0.5 meter, the EFFORT force moves 0.51 meters. Conclusions? Because the 1 kg weight is not really 1 kg, but rather 1.002 kg, the effort data collections will be slightly off. Extra force will be necessary to lift the heavier weight. Two Pulleys LOAD is the weight of the 1-kg mass. LOAD (L) = 9.8 Newtons LOAD DISTANCE is the height the mass is raised LD = 0.5 meters EFFORT is the force applied to move the load upward at a constant speed. EFFORT (E) = 5 Newtons EFFORT DISTANCE is the length of string pulled ED = 0.98 meters Is L x LD = E x ED? 9.8 x 0.5 = 5 x 0.98 Yes The Mechanical Advantage (MA) = LOAD/EFFORT For this Pulley MA = 9.8/5 = 1.96. What about the differences in distances moved? 0.48 meters If the LOAD moves up 0.5 meter, the EFFORT force moves 0.98 meters. Conclusions? When two strings support the same weight, the effort needed to pull up the weight is half the effort needed if there were only one string. Due to a constant load, the Mechanical Advantage is altered.

Efficiency is an indication of how much of the work is lost to friction. Work output is the outcome = LOAD x LD which is Wo = 9.8-N x 0.5 m = 4.9-Joules for every trial. Work input is the amount of effort you put into the project =...