Test 3

for physics

frequency formula

1 / time period

units of frequency

1 sec = hertz

crest

high points of the wave

Troughs

are the low points of the wave. (valley)

Heat

The energy transferred between objects that are at different temperatures

Heat equation

q= cm ∆T ( m is mass, C is specific heat and

Heat depends on

1. Mass (m) of the objects.

2. Change in temperature (ΔT)

3. Type of material defined by the specific heat (C).

Units of heat

Nm (J), kg m2/s2, Calorie, kilocalorie, kilojoules (kJ) , Kilowatt-hour (kwh), foot-pound

Amplitude

distance from the midpoint to the crest.

Specific heat

A measure of the object's resistance to change in temperature. The amount of heat needed to raise the temperature of 1 kg of mass by 1C.

Specific heat equation

C = Q/ m ΔT

Specific heat units

J/kg0C, Calorie /g0C

Latent heat (L)

A measure of an object's resistance to change in phase. The amount of heat needed to complete the phase change of a unit mass.

Conduction

Transfer of heat through direct contact.

Convection

Transfer of heat by buoyant mixing in a fluid. (Liquids and gases).

Radiation

The transfer of heat through electromagnetic waves (light).

Thermal expansion

Most substances expand when heated and contracts when cooled

Linear thermal expansion equation

Δ l = α l ΔT ( l is original length, ΔT is change in temperature, α is the coefficient of linear expansion )

Temperature (T)

Temperature is proportional to the average kinetic energy of atoms and molecules in a substance.

Temperature scales

Celsius (C) Scale: Freezing 0C, Boiling 100 C

Fahrenheit (F) Scale: Freezing 32F, Boiling 212F

Kelvin (K) Scale: Freezing 273K, Boiling 373K.

Absolute zero

This is the coldest possible temperature; it is impossible to go below this temperature. · 0 K is the absolute zero.

Use the equation below to convert temperature in degree Celsius to Fahrenheit. F] = 9/5[C] +32

EX: 200C =? 0F

answer: = 68 F

Use the equation below to convert temperature in degree Fahrenheit to Celsius. [C] = 5/9 [F - 32]

EX: 14F =? C

10 C

1) Calculate how much heat is required to bring 400 g of water from a temp of 65 C to a temp of 100 C? Specific heat of water is 4180J/kg C

answer: 58,520 J

1) How much heat is needed to raise the temp of 5 kg of Silver from 20C to 960C? Sp. Heat of Silver is 230J/kg C.

Answer: 1081000 J

1) An iron railroad is 700ft long when the temp is 30C. What is the length when the temp is -10C?

Coefficient of linear expansion for iron is 12 x 10-6 /0c.

Answer: - .336 ft

1) The center span of a steel bridge is 1200 meters long on a winter day when the temp is -50C. How much longer is the span on a summer day when the temp is 350C?

Coefficient of linear expansion for steel is 12x10-6/oc.

Answer: 0.576 m

Buoyancy

The apparent loss of weight experienced by objects submerged in fluid.

Buoyant force (Fb)

The upward force a fluid exerts on an object wholly or partially submerged in it. Buoyant force is a vector with a upward direction only.

Unit of measure of buoyant force

N (kgm/s^2), dyne, tons pounds, ounces etc.

Buoyant force is due to _____

pressure difference in the fluid

If there is no pressure difference in the fluid ______

there is no buoyant force

Volume principle

The volume of a completely submerged object is equal to the volume of the fluid it displaces.

Archimedes's Principle

For a completely or partially submerged object, buoyant force is equal to the weight of the fluid displaced by the object.

Pascal Principle

If an external pressure is applied to a confined fluid (fluid at rest), the pressure at every point within the fluid increases by that amount.

Bernoulli's principle

pressure is lower where a fluid is flowing faster, and pressure is higher where fluid is flowing slower.

If an object sinks that means density of the object is ______

is more than the density of the fluid and the weight of the object is more than the buoyant force.

If an object rises that means density of the object is_____

less than the density of the fluid and the weight of the object is less than the buoyant force.

If an object floats that means density of the object is______

less than the density of the fluid and weight of the object is equal to the buoyant force.

If an object maintains neutral buoyancy that means density of the object is ______

equal to the density of the fluid and weight of the object is equal to the weight of the object.

Pressure (P)

Force per unit area.

Pressure formula

Pressure = Force / area

If a force is applied on less area, then there will be _____

more pressure.

Units for pressure

Metric units of pressure: N/m² = Pascal (Pa), atmosphere (atm),

                                                 Millimeter of mercury (mm of Hg).

British unit of pressure: Pounds per squared inch (psi) = lbs /in²

 

Pressure due to liquid or liquid pressure

•   Liquid pressure depends on the depth of the liquid (how deep the liquid is)

•      Liquid pressure depends on the density of the liquid.

Denser the liquid is more liquid pressure.

• Liquid pressure depends on the gravity g = 9.8m/s²

pressure due to liquid formula

D x G x H ( density x 9.8 x depth of liquid )

density

mass per unit volume.

Density formula

mass / volume

Wavelength (λ)

is the distance from the top of the one crest to the next crest or distance between two successive like points

wavelength units

m/wave, cm/wave

Frequency (f)

Number of waves passes any point per second or number of to and for vibrations in a given time.

If given time unit is days, then frequency unit will be _____

1 day

If given time unit is minute, then frequency unit will be _____

1 minute 

Period or time period(T)

time to complete one vibration

Unit of period or time period

second, minute, hour, days, year

Wave motion

waves transport energy and not matter.

Wave speed (v)

how fast a disturbance moves through a medium.

Wave speed formula 

Wavelength (λ) x Frequency (f)

Wave speed Units

m/s, cm/s , mph, feet/s etc .(same as speed units)       

EMW (Electromotive wave)

EMW produced by accelerated charged particles. That means only charged particles like electrons, protons, ions can produce EMW when they accelerate.

Sound waves

Sound waves are longitudinal wave. Speed of sound in air or other gases depend on the temperature.

sounds waves formula

 v = 331m/s + 0.6m/s/⁰C x Temperature in Celsius.

Echolocation

a wave sent out. If it encounters an object, it reflected back. By timing how long it takes for the echo to return, the distance to the object can be determined.

What does the K represent in Coulombs law formula?

K = 9 × 10^9

Echolocation formula

Speed (v) =(2 x distance )/ time

An EM wave traveling through a vacuum has a frequency of 2 x 10^14 Hz. Determine the wavelength of the wave. Speed of light c = 3x10^8m/s

 1.5 x 10^-6 m.

A 3500 Hz wave is observed to have a wavelength of 2.3 m/wave.

a) Determine the speed of wave?

8050 m/s

A 3500 Hz wave is observed to have a wavelength of 2.3 m/wave.

b) If a second wave is traveling through the same medium and has a frequency of 55,811Hz. What is its wavelength?

0,144 m.

3. A person stands in front of a cliff and gives a shout. 0.8seconds later the person heard the echo. The speed of sound is 347m/s. How far away is the cliff?

=138.8 m.

 You are standing on a canyon edge and give a shout. After 3.7 seconds passed, you heard your echo. The temperature is 20.6 degree Celsius. How far away is the cliff?

V =   343.36 m/s

Doppler Effect

The apparent change in frequency of the sound observed by the observer when there is a relative motion between the source of the sound and the observer

When was the object completely gas?

t = 0 min to 15 min

How long was the object completely liquid?

t = 90 min – 40 min = 50 min

Over what temperature range was the object solid?

25 to 0 degrees Celsius

At what temperature did the object freeze?

25 degrees Celsius

Charge (q):

A physical property of certain subatomic particles that is responsible for electl anagnetic phenomena

Charge units

Units: Coulomb (C), micro coulomb (μ C), mill coulomb (m C).
• 1mC = 10 ^ -3 coulomb (C)
• 1μ C = 10 ^ -6 coulomb (C).

Charge on proton is positive

1.6 x10^-19 coulomb

Charge on electrons is negative

- 1.6 x 10^-19 coulomb.

Ionized atom

ue to physical and chemical interactions an atom can gain
one or more electrons or lose one or more electrons. Then atom is said to be
ionized

Positive Ion

atoms lose one or more electrons.

Negative ion:

atoms gain one or more electrons

Coulomb’s law:

electrical force acting between two charged particles is directly proportional to the product of the charges and inversely
proportional to the square of the distance between them.

Coulomb’s law formula

F= K q1 q2 / d2