## Glossary of physics exam 1

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- length
- meter [m]

measurement of space direction

- time
- second [s]

continuous forward flowing of events

- mass
- kilogram [kg]

amount of matter

- electric current
- Ampere [A]

property of matter

- temperature
- Kelvin [K]

- intensity of light
- Candela [cd]

- Speed
- Object travels divided by the time it takes to travel that distance.

Speed(in m/s) = distance (in m) / time (in s) s = d / t

- Velocity
- has the same numerical value as speed but velocity always includes information on the direction of travel. The speed of a car may be 50 km per hour, while the velocity is 50 km per hour due west. This means velocity has a magnitude and a direction.

- Acceleration
- is the amount of change in velocity divided by the time it takes the change to occur.

acceleration( in m/s2)= [final velocity - initial velocity (in m/s)] / time ( in s)

a = (vf - vi) / t

- The First Law:
- An object in motion stays in motion until acted on by a force.

- The Second Law:
- The greater the force, the greater the acceleration; but the more massive the object being acted or by a given force, the smaller the acceleration.

- The Third Law:
- whenever a force is applied to an object, that object simultaneously exerts an equal and opposite force

- uniform motion
- if it travels in a straight line at constant speed.

All other motions are called accelerated

- Newton's law of universal gravitation .
- Between any two objects in universe there is an attractive force (gravity) that is proportional to the masses of the objects and inversely proportional to the distance between them.

- Gravity
- force (= m * a)

g=9.81 m/s2

- Weight
- mass * acceleration from gravity

W = m * g

force (in N)

- Inertia
- is the tendency of an object to resist any change in its motion. Inertia is directly related to how much mass an object has -- how much stuff is there.

- Force
- mass * acceleration

N = kg m /s^2

- Work
- Work is equal to the force that is exerted times the distance over which it is exerted

In equation form:

work (in Joules) = force (in Newtons) * distance (in meters)

- Energy
- ability to do work

J

power * time

- Power
- is defined as the rate at which work is done, or at which energy is expended.

In words:

Power is the amount of work done, divided by the time it takes to do it. In equation form:

power (in watts) = work (in joules) / time (in seconds)

P = W / t

- Energy of Motion -- ``Kinetic Energy''
- vibrating

moving

turning

is energy associated with moving objects

- Stored Energy -- ``Potential Energy''
- springs

chemical

electrical

gravitational

is energy waiting to be released.

- Properties of a substance which depends on the temperature:
- Volume: (in general, the volume increases with increasing temperature)

States: solid - fluid - gas

Properties of materials: elasticity, electric resistance, speed of sound

- Pressure
- Pressure is defined as force per area.

The area is measured in m2, the force in N.

The unit of pressure is N / m2

P = F / A

- Mechanical Waves
- a disturbance moving through a medium.

Source of disturbance -- vibrating object

Medium to disturb -- but NO net displacement

Adjacent portions of medium are connected -- to carry the disturbance

Carry Energy and Momentum

- Frequency:
- f=1/t

Unit is Hertz : [Hz] = [1/s]

- Hooke's Law
- FS = -k * x

Force = - constant * [displacement from equilibrium]

F = -k * x = m * a

a = -(k/m) * x

- fundamental frequency
- depends

on radius R of drum

tension of membrane T

material of membrane d