PASCO ME-6855 Tension Protractor - Manual (Page 7)

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T e n s i o n P r o t r a c t o r E x p e r i m e n t 1 : S t a t i c E q u i l i b r i u m w i t h U n e q u a l A n g l e s
5
Similarly, Equation 1-3 yields
(eq. 1-8)
(eq. 1-9)
Or, the sum of the magnitudes of the forces up must equal the sum of the magnitudes of
the forces down:
(eq. 1-10)
(eq. 1-11)
Procedure
1. Clamp two rods (90 cm long) vertically to the table, approximately 80 cm apart.
Attach two Tension Protractors (oriented with zero degrees horizontal) to a cross rod,
and clamp this rod between the vertical rods as shown in the Figure 1.3 (but don’t
attach the mass yet).
Figure 1.3: Set-up
2. Zero the force scale of each Tension Protractor: Without anything attached to the Ten-
sion Protractor string, adjust the thumb screw in the back until the force scale reads
zero.
3. Zero the angle scale of each Tension Protractor: Hang a small mass (10 g) from the
hook. Rotate the outer ring to align the 90° mark with the string (Figure 1.4).
4. Cut a string about 60 cm long. Tie a loop about 25 cm from one end so that the string
length on one side of the loop is about 20 cm and the string length on the other side of
the loop is 35 cm. Tie one end of the string to the wire hook on one of the Tension
Protractors and tie the other end of the string to the wire hook of the other Tension
Protractor. Hang a 500 g mass from the string loop (Figure 1.3).
5. Read the magnitude of force and the angle for each string and record them in
Table 1.1.
F
1 y
F
2y
F
3 y
– + 0 =
F
1
θ
1
sin F
2
θ
2
sin F
3
– + 0 =
F
1y
F
2y
+ F
3y
=
F
1
θ
1
sin F
2
θ
2
sin + F
3
=
Figure 1.4: Zero the
angle scale