PASCO ME-9502 Statics System - Manual (Page 85)

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M o d e l N o . M E - 9 5 0 2 E x p . 1 4 : S i m p l e M a c h i n e s – T h e P u l l e y
0 1 2 - 1 2 8 7 6 B 81
Exp. 14: Simple Machines–The Pulley
Equipment Needed
Theory
In previous experiments, you used pulleys to change the direction of applied
forces. However, systems of pulleys can be arranged to translate relatively small
applied forces into much larger forces, much the same way as a lever or inclined
plane. In this experiment you will take a second look at pulleys and investigate
how systems of pulleys can be used to amplify the applied force as work is done.
In an ideal pulley system there would be not friction in the pulleys. For example,
the applied force would be transferred completely to the hanging mass.
As with the lever and the inclined plane, pulley systems can be understood by
analyzing either the forces acting on the system or the work performed on and by
the system. In this experiment you will investigate several pulley systems.
Procedure
The effects of friction are more noticeable in this experiment than with the lever or the inclined plane. Start by
investigating the effects of friction in the pulleys.
1. Put 200 g of mass on a mass hanger and use the Spring Scale to
measure the total weight, W, of the mass hanger plus mass. Record
your measurement.
• Weight, W = ______________
2. Put the Spring Scale and two Pulleys on the Statics Board as
shown and use thread to attach the Spring Scale to the hanging
mass. Record the reading of the force, F, on the Spring Scale.
• Force, F = _______________
Question
• How does the force reading, F, on the Spring Scale for the pulley
setup compare to the weight, W, of the hanging mass?
3. Set up each of the three pulley systems shown below. For each
pulley system, perform work on the system by slowing raising the Spring Scale. Measure and record the fol-
lowing:
Item Item
Statics Board and Pulley Mounted Spring Scale
Large Pulley and Small Pulleys (2) Double Pulley Block
Mass and Hanger Set Thread
Symbol Description Symbol Description
F Force reading on the Spring Scale d
2
Distance that the hanging mass is raised
W/F Ratio of weight of hanging mass to force Work Work done by raising the Spring Scale (F x d
1
)
d
1
Distance that the Spring Scale is raised
E
Change in gravitational potential energy (W x d
2
)
Fig. 14.1: Simple Pulley
Mass
Force
Figure 14.2: Equipment Setup
Pulley
Spring
Scale
Hanging
Mass
Pulley