Pendulum types:
Simple pendulum — a ball on a string(light string):
- The ball is the mass
- Displace the ball to move
- All mass concentrated at one point
- The size of the mass is smaller compared to the length of the string
- The string should be massless
- An idealization
- No perfect simple pendulum
Physical pendulum — a beam with a pivot:
- The beam is the mass
- Displace the beam to move
- Mass distribution could be arbitrary
What makes a pendulum move?
- As long as the pivot is not directly on top of the center of mass
Periodic — Something that repeats itself
Equilibrium — at 0
Force — an influence that can change the motion of an object
Newton’s law of motion:
- The object will stay in constant velocity (speed and direction) if the forces applied to its are balanced (no net force)
- Force = mass * acceleration(change in velocity / change in time)
- Every force has an equal (magnitude) and opposite reaction force
Pendulum formula:
- T=2pi(sprt(L/g))
- T — period
- L — pendulum length
- g — acceleration due to gravity
- g=-(GM)/r²*r^
- G — gravitational constant (6.674 30 x 10–11 m3 kg-1 s-2)
- M — mass of the field source
- r — distance between two point-like masses
- r^ — unit vector directed from the field source to the smaller sample mass
Experiment:
- Build either a simple or physical pendulum
- Oscillate twice in 1 second
- a strand of string
- a ruler
- a protractor
- a watch for time keeping
- laptop / paper to keep track of data
My data and results
https://docs.google.com/spreadsheets/d/1-c6LEF470KhSw1qceDw67NQChSR-28anAVnzO6uoR7A/edit?usp=sharing
