Hearing Science: Physics Recap

Why do we need to know about the concepts of physics for hearing? (Name five reasons: Go Park Betty’s Truck, EDdy!)

Physics explains how sound is generated, the properties of sound, how sound behaves, how sound is processed as it travels through the auditory system and how sound is processed through electronic/digital science.

Define Mass:

How much matter a substance or object has.

How does mass differ from weight?

Mass differs from weight because weight is correlated with the force of gravity. One can be weightless but not massless.

Why is mass important to study regarding an auditory system? It Oozes!

Adding mass to a system can either impede the system or affect the outcome of the system.

Define Density:

The amount of matter in a given unit of volume.

Why is density important to study regarding an auditory system?

Boundaries: the density of a boundary affects what you do and don’t hear, it comes into play when you look into any object that generates sound. (Ex: floor, walls [concrete vs plaster matters!])

Define Elasticity:

(also referred to as “stiffness”) The property of matter that allows it to return to its original state after it has been disturbed from its original state; this can be a source of motion.

Why is elasticity important to study regarding an auditory system? Grandma Tina’s AGING!

Elasticity affects how sound is generated and how sound travels, movements of certain parts of the auditory system require stiffness to hear, and losing that (often with aging) can lead to hearing loss.

Define Displacement:

The length of distance between point A and point B, regardless of the path taken; this doesn’t vary.

Define Distance:

The path one has to take to get from point A to point B; this varies.

Why are displacement and distance important to study regarding an auditory system?

It shows how sound reacts in movement and distance.

Define Speed:

How fast something is moving.

Define Velocity:

Rate of change in displacement; is a combination of both speed and direction; is constant. (Ex: cruise control at 60 mph.)

Define Acceleration:

Rate of change in velocity; is the change in speeding up and slowing down including direction. (Ex: cruise control at 0 to 60 mph.)

On this car drawing, label where the velocity is demonstrated.

A + D

The speed remains the same on both parts, there is constant movement.

On this car drawing, label where the positive acceleration is demonstrated.

B

It is easier to glide down the hill, changing speed.

On this car drawing, label where the negative acceleration is demonstrated.

C

It takes force to change the speed going up the hill again, as gravity is stronger than the mass of the object.

Define Force:

Interaction between two objects or between the object and its environment.

It takes force to accelerate, move, or stop an object because objects have mass.

Determined by the mass (size) and the acceleration of an object.

Define Newton’s 1st Law:

An object at rest will remain at rest and an object in motion will remain in motion unless acted upon by an external force - including something you can’t see, such as gravity.

(Ex: a boy skateboarding and comes upon a rock, causing him to tumble forward and off of the board; OR floating endlessly through space.)

This applies most to Inertia, in motion or in no motion.

Define Newton’s 2nd Law:

The amount of acceleration of a body is proportional to the acting force and inversely proportional to the mass of a force; smaller objects move faster with force and vis versa.

(Ex: pushing a car in neutral, more force required to move a heavier object [one is significantly more in mass than force])

Define Newton’s 3rd Law:

For every action, there is an equal and opposite reaction.

(Ex: recoil on a spring, or walking a dog and needing to pull with the same force the dog wants to go)

What do Newton’s 1st and 2nd law explain?

An object will not change its motion unless an external force acts on it.

Define Equilibrium:

The state of balance or stability where an objects state of motion doesn’t change over time.

If not change in motion, the NET Force is zero and the opposing forces are equal.

(Ex: the computer on your desk not crashing through the table and to the floor, gravity doesn’t pull the computer)

Does having equilibrium mean there is no force?

No, gravity always acts on earth, there is just an opposing force cancelling it out. Force is always applied.

Define the Law of Universal Gravitation:

Every object in the universe attracts every other object with force directed toward its center and that is proportional to the square of the distance between them.

The gravitational pull is proportional with the size of the mass, but inversely proportional to the distance between them.

(Ex: the sun has a larger gravitational pull for earth, but the sun and the earth have enough distance between them that we can orbit without being pulled to the sun’s center; OR I’m not being pulled into the earth’s center because the NET Force is equal to zero and the ground is stopping gravity)

Define Gravity:

Universal phenomenon where two objects are attracted to each other.

(Ex: things fall to the ground because there is a greater opposing force, gravity, than the mass of the object.)

What is gravity dependent on?

Masses of the objects and the distance between them.

Define Weight:

Force of gravity acting on an object.

Define Momentum:

The product of velocity and mass; things in motion have momentum.

I have to apply force to change my momentum.

Define the Law of Conservation of Total Momentum:

The total momentum of things will never change unless acted upon by an outside force.

When two objects collide the momentum can transfer but the total momentum doesn’t change before or after the collision.

(Ex: bike hits a pothole and you tumble over your handles head first.)

Define Energy:

The ability or capacity to work.

In order for me to accomplish a task, I have to apply energy (acoustical, mechanical, electrical, chemical, etc.).

Define Potential Energy:

Any object at rest is storing energy.

“Future work”, I can store energy to compete a task.

Define Kinetic Energy:

Energy in use.

A completed task is work, and work is energy used.

Define Conservation of Energy:

Energy can change from one form to another but cannot be created or destroyed.

Energy is never lost, just converted.

On this drawing, where is the Kinetic Energy demonstrated?

A + C

The ball is in motion, using energy to go up the hill and to go down as well.

On this drawing, where is the Potential Energy demonstrated?

B

The ball slows down enough to store energy for the upcoming pathway down.

Define Power:

The rate of which a system is gaining or losing energy.

Applying more power will accomplish more work, you burn energy faster but work is done faster too.

(Ex: working out, you can burn energy faster if you burn through a workout to your full physical extent.)

Greater force, greater velocity, higher power.

On this drawing, where is the Potential Energy demonstrated?

C

The ball slows down enough to store energy for the upcoming pathway down.

On this drawing, where is the Kinetic Energy demonstrated?

B + D

The ball is in motion, using energy to go up the hill and to go down as well.

On this drawing, where is the Acceleration demonstrated?

E + G

The ball is growing and changing in speed to get up the hill.

On this drawing, where is Velocity demonstrated?

F

This is a constant speed every time the ball hits this part of the hill on repeat.

On this drawing, where are the Equilibrium and Applied Force demonstrated?

A

The ball is at rest until there is force applied to get it up the hill.

Please explain how mass and stiffness (elasticity) play a role in sound generation and sound propagation (travel).

Every object has mass and some degree of stiffness. The frequency of vibration (or resulting pitch) will depend on the amount of mass and stiffness of an object during sound generation. Altering mass and/or stiffness of the object can change the resulting sound.

In order for sound to travel, it must have a medium. The medium can be either solid, liquid, or gas. How well the sound travels and whether or not energy is dampened or filtered out will depend on the mass and stiffness characteristics of the medium.

Which Law of Motion essentially defines inertia? Please define inertia and explain how it can occur in two states. Make sure to identify those two states in your answer.

Newton’s First Law of Motion defines inertia. Inertia is the object’s resistance to a change in its current state of motion (in motion or at rest). If an object is at rest, it will want to stay at rest. If an object is in motion, it will want to stay in motion. It will take an outside force to change these states of inertia.

Describe the difference between potential energy and kinetic energy. Then provide an example that illustrates conversion from potential energy to kinetic energy and back to potential energy. DO NOT use an example provided in class.

Potential energy is energy that is stored for FUTURE work. Kinetic energy is energy used DURING work. These two energies can be reversed.

For example: I am holding a paper airplane in my hand. The plane has potential energy when it is being held in my hand steady waiting to be released – it has the potential to use energy to fly in this state. Once I pull back my arm and release the plane, the plane now has kinetic energy because it’s doing the work of flying. When the plane lands and comes to a stop, the plane once again has potential energy.