1. Simple Harmonic Motion
Vibrations and Waves
Simple Harmonic Motion

2. Hooke’s Law Periodic motion – repeated motion
Usually back and forth over the same path at regular time intervals
Equilibrium position – the point in the motion where the net force on an object is zero
At the equilibrium point, velocity reaches a maximum
At maximum displacement. Spring force and acceleration reach a maximum
Velocity is zero

3. Hooke’s Law

4. Hooke’s Law
Simple harmonic motion – vibration about an equilibrium position in which a restoring force is proportional to the displacement from equilibrium
Hooke’s Law = spring force = -(spring constant * displacement)
Felastic = -kx
k is measured in N/m
Felastic is measured in N

5. Hooke’s Law
Remember that stretched or compressed objects have elastic potential energy
This causes the object to repeat its motion

6. The Simple Pendulum A simple pendulum consists of a bob and string
The bob – the part of the pendulum that swings back and forth
We disregard the mass of the string, air resistance, and friction
The restoring force of a pendulum is a component of the bob’s weight
The same conclusions that we drew with springs about force, displacement, and velocity are true for pendula as well, with small angles

7. The Simple Pendulum

8. The Simple Pendulum
At the equilibrium point, velocity reaches a maximum
At maximum displacement, force and acceleration reach a maximum
Velocity is zero
Gravitational potential energy increases as a pendulum’s displacement increases
Kinetic energy increases as the pendulum nears the equilibrium point

9. The Simple Pendulum

10. The Simple Pendulum