Simple Harmonic Motion Flashcards
What characterizes an object’s motion as simple
harmonic?
SHM is characterized by moving back and fourth around a central point (equilibrium) where a restoring forces works to bring it back to this point. It repeats in regular intervals.
List four examples of simple harmonic motion
Car suspension, playground swing, metronome, ball on a string
Does the acceleration of a simple harmonic oscillator
remain constant during its motion? Is the accelera-
tion ever zero? Explain.
Acceleration is greatest at maximum displacement and zero at the equilibrium
A pendulum is released 40° from its resting position.
Is its motion simple harmonic?
SHM only applies to <15 degrees. This would follow more complex motion
April is about to release the bob of a pendulum.
Before she lets go, what sort of potential energy does
the bob have? How does the energy of the bob change
as it swings through one full cycle of motion?
Before she releases there is potential gravitational energy. When she releases it, it has kinetic energy.
An ideal mass-spring system vibrating with simple
harmonic motion would oscillate indefinitely.
Explain why.
Without any outside forces, the system would continuously convert kinetic to potential without any net loss (friction, air resistance)
In a simple pendulum, the weight of the bob can be
divided into two components: one tangent to the
direction of motion of the bob and the other perpen-
dicular to the direction of motion of the bob. Which
of these is the restoring force, and why?
The restoring force is tangent because it pulls the bob back towards equilibrium causing it to oscillate
A child swings on a playground swing. How many
times does the child swing through the swing’s
equilibrium position during the course of a single
period of motion?
The child has to pass through twice, once through the equilibrium point, and then once back through the equilibrium point
What is the total distance traveled by an object
moving back and forth in simple harmonic motion in
a time interval equal to its period when its amplitude
is equal to A?
4A
How is the period of a simple harmonic vibration
related to its frequency?
The period is equal to 1/f
What happens to the period of a simple pendulum
when the pendulum’s length is doubled? What
happens when the suspended mass is doubled?
The period would increase by the square root of two, but doubling the mass would not change anything because they all experience the same free fall acceleration
A pendulum bob is made with a ball filled with water.
What would happen to the frequency of vibration of
this pendulum if a hole in the ball allowed water to
slowly leak out? (Treat the pendulum as a simple
pendulum.)
The frequency would remain constant because mass has no effect on frequency
If a pendulum clock keeps perfect time at the base of
a mountain, will it also keep perfect time when
moved to the top of the mountain? Explain.
No, because a pendulum if affected by gravity and would run slower at the top than at the base
If a grandfather clock is running slow, how can you
adjust the length of the pendulum to correct the
time?
If you were to decrease the length of the pendulum, the period would decrease making it run “faster”
A simple pendulum can be used as an altimeter on a
plane. How will the period of the pendulum vary as
the plane rises from the ground to its final cruising
altitude?
As the plane rises, the period would increase, causing it to run more slow. As the plane decends, the period would decrease
Will the period of a vibrating mass-spring system on
Earth be different from the period of an identical
mass-spring system on the moon? Why or why not?
A mass-spring system is not affected by gravity so it would be the same on earth and the moon
._According to Hooke’s law, the force exerted by a spring on an object is proportional to
displacement from equilibrium position
In any system in simple harmonic motion, the restoring force acting on the mass in the
system is proportional to
displacement
The spring constant in a given oscillating mass-spring may be
changed by (increasing/decreasing) mass
changing the mass will not change K, but T. So, neither
In an oscillating mass-spring system, the velocity of the mass is greatest when the mass
is at what location?
The velocity is greatest at its equilibrium point
The period of a pendulum may be decreased by
decreasing the length of the pendulum
As the swinging bob of a pendulum moves farther from its equilibrium position, the
pendulum’s _______________ increases.
acceleration
You have constructed an oscillating mass-spring system for an experiment. In order to
increase the frequency of the system, you could
decrease the mass
In a system in simple harmonic motion, the amplitude depends on
initial displacement and initial energy input
