Physics

Question 1

what the equation for Pressure?

Answer 1

P = F/A

pressure (Pa) = force (N) /area (m^2)

Question 2

What is the equation for mass density?

Answer 2

pm = m/V

mass density (kg/m^3) = mass (kg) / volume (m^3)

Question 3

What is the equation for weight density?

Answer 3

pw = w/V

weight density (N/m^3) = weight (N) / volume (m^3)

Question 4

How is weight density obtained from mass density?

Answer 4

by multiplying mass density by the acceleration of gravity (9.8m/s^2)

Question 5

in what unit is pressure measured in for GASES?

Answer 5

atmospheres (atm = 1 at sea level, 0 degrees celsius)

Question 6

waves have three measurable properties which are…

Answer 6

wavelength, amplitude, frequency

Question 7

describe the relationship between wavelength and frequency

Answer 7

they are inversely proportional

• longer wavelength = lower frequency
• shorter wavelength = higher frequency

Question 8

Wavelength can be measured in …

Answer 8

Angstroms (A) or nanometers (nm)

Question 9

What is reflection, refraction and absorption?

Answer 9

• reflection occurs when light (travelling as particles) hit a smooth or bumpy, bright surface, causing it to project back towards its origin either in a straight line or in multiple directions.
• refraction is when light (travelling as particles) hits a transparent surface, causing it to travel past the surface to the other side.
• absorption is when light is absorbed into the medium or surface

Question 10

what happens to light when it travels through a surface that is a different medium to air?

Answer 10

the wavelength of the light will change, causing it to change in direction, known as angle of refraction.

Question 11

how is colour perceived?

Answer 11

• by the way different objects reflect, refract or absorb light.
• different objects reflect only certain wavelengths of light and absorb the rest.
• the light that is reflected is the colour that is perceived.
• white light is a reflection of all the wavelengths.

Question 12

What are the main colours of the light spectrum?

Answer 12

red, yellow, blue

Question 13

How is colour and light detected by the eyes?

Answer 13

by cone cells and rod cells in the retina

Question 14

electricity exists because..

Answer 14

all particles which make up the universe are charged (neg/pos)

Question 15

an electric current is…

it is measured in…

Answer 15

• the movement or flow of charged particles from one place to another
• volts or amperes

Question 16

electric charge is…

it is measured in…

Answer 16

• the positive and negative forces which make up atoms

- coloumbs

Question 17

What is coloumb’s law?

Answer 17

a measure of the electrical force between two charged particles, which is inversely proportional to the distance between them.

Question 18

What is an electric field?

Answer 18

a field of electrical charge surrounding a particle, which is equivalent to its net charge.

• E = Fc/q
• electric field = couloumb force / net charge or particle

Question 19

What is an Ampere?

Answer 19

• the number of coloumbs passing a certain point per second
• I = C/s
• electric flow = coloumb/second

Question 20

What is a Volt?

Answer 20

• the unit measuring the amount of pressure pushing an electric flow through a circuit.

Question 21

What are the relationships between conduction of an electric current and diameter, length, voltage and resistance of a wire/circuit?

Answer 21

the conduction of a current is directly proportional to the diameter and voltage and inversely proportional to the length and resistance.

Question 22

What are the three equations for Ohm’s Law?

Answer 22

• Voltage (V)
• Resistance (R; measured in ohm’s)
• Current (I; measured in amperes)

V = IR
R = V/I
I = V/R

Question 23

What are the four components of an electric circuit?

Answer 23

• generator (battery)
• conductor (wire)
• resistor
• load (electrons)

Question 24

What are the 4 components of sound waves? and how do they relate?

Answer 24

• wavelength (lambda)
• Frequency (f; Hz)
• Amplitude
• Speed (k)

Wavelength = k / f

Question 25

How does pressure in the medium in which sound waves travel, affect them?

Answer 25

• higher pressure leads to lower frequency and lower speed of travelling through the medium
• lower pressure leads to higher frequency and greater travelling speed.

Question 26

what is the mass density of water for one cubed meter?

Answer 26

1000kg/m^3

Question 27

what is the hearing range (frequency) for humans?

Answer 27

20 - 20,000 Hz

Question 28

What is the difference between light and sound waves?

Answer 28

• light waves do not require a medium for travel, sound waves require a medium hence cannot travel through a vacuum.
• there is no particle theory for sound waves