PURPOSE: To show the tension in the string exerted by a swinging pendulum.
DESCRIPTION: The spring scale reads the tension in the string as the pendulum swings, about 25 Newtons at the center and 19 Newtons at the ends of the swing with a bob mass of 1.1 kG. In this setup:
F (center) = mg + mrw^2 = mg (3 - 2 cos a)
F(end) = mg cos a
where by conservation of energy
m v^2 /2 = m r^2 w^2 /2 = mgr (1 - cos a)
m r w^2 = 2mg ( 1 - cos a)
REFERENCES: (PIRA unavailable.)
EQUIPMENT: Pendulum with bifilar support, 40 N spring scale, 22 N (5 lb) weight.
SETUP TIME: 5 min.
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