mocks😭

force

push or pull

what can force cause?

change in shape, speed, direction of an object

contact forces

objects must touch

what an example of contant forces?

air resistance, spring force, etc.

non-contant forces

objects are physically separated

what’s an example of non-contact forces?

gravitational force, nuclear, etc.

what’s unit of force?

Newtons

what’s the equation that links mass with weight?

F=ma (F: force in newtons, m: mass in kg, a: acceleration in m/s² or N/kg)

What’s the gravity on Earth?

9.8 m/s²

mass

a measure of the amount of staff in an object and gives a measure of how difficult it is to get moving or to stop

• never changes

vector quantities

a quantity that has both magnitude & direction

• can be represented using an arrow

scalar quantity

a quantity that only has magnitude

what happens when a several forces act on an object?

they can be replaced by a single force (resultant force) that has the same effect

how do you calculate the resultant force?

subtract the smaller force from the larger force

• constant velocity = terminal velocity

what is a free body diagram?

• object shown as a point

• forces are drawn as arrows

• the length of the arrow indicates the magnitude of the force

• the direction of the arrow shows the direction of the force

what are the steps of drawing a scale diagram?

1) draw arrows at the correct angles to represent the forces

2) draw lines to make a parallelogram

3) measure the diagonal of a parallelogram (this is your resultant force)

speed

a measure of the distance an object travels in a certain time

what’s the formula of speed?

speed = distance / time

velocity

a vector that tells us how fast an object is moving and its direction

displacement

a vector that tells how far an object has moved and the direction it move in

how do you draw a displacement time graph?

acceleration

the rate at which an object changes its speed

what are the 2 factors that affect acceleration?

how the speed changes and how much time the change in speed takes

what’s the formula for acceleration?

acceleration = change in speed (m/s) / time (s) or final velocity - initial velocity / time taken

what’s the unit of acceleration?

m/s²

constant acceleration

speed or velocity is increasing at the same rate over the same time period

how to draw a velocity time graph?

how do you find the area under velocity time graph?

multiply the value on the horizontal axis with the value on the vertical axis

• split the area into triangles & rectangles

• area of triangle = base x height / 2

what does newton’s second law state?

the acceleration of an object depends on the mass of an object and the force applied

stopping distance

how far a car moves between the driver noticing something in front of them and the car coming to a stop

what is the stopping distance affected by?

thinking and braking distance

braking distance

how far the car travels once you’ve put your foot on the brake

what’s the formula of stopping distance?

stopping distance = thinking distance + braking distance

how is energy useful?

energy has to be transferred using energy carriers

what unit is energy measured in?

Joules

what is the main property of energy?

energy cannot be created or destroyed

what are some examples of energy sources?

solar, nuclear fusion, tidal, etc.

how are winds caused?

the heating effect of the sun

renewable energy

energy that is being or can as its used

how does geothermal energy work?

heat from the Earth’s core brings water and steam to the Earth’s surface which can be converted to generate electricity

what are the benefits of hydroelectric power?

• no waste is produced during energy production

• reliable water source for communities

• helps with flood control and irrigation support

where can waves transfer energy?

all waves can transfer energy from one to another without transferring matter

Waves can transmit through what?

solid, liquid, gases, and empty spaces

frequency

the number of complete waves passing a fixed point, in a given amount of time

• measured in Hertz (Hz)

wavelength

the distance between the point on one wave and the same point on the next wave

• measured in metres (m)

amplitude

the distance from the maximum of the disturbance to the initial position

longitudinal waves

the particles vibrate parallel to the direction in which the wave of energy is traveling

• places where the particles are bunched together are called compression

• where they are furthest apart are called rarefactions

• example: sound waves

transverse waves

up and down motion from left to right therefore then particles vibrate at 90 degrees

what’s the formula that links speed, wavelength, and frequency?

• speed = frequency x wavelength

• frequency = speed / wavelength

• wavelength = speed / frequency

what are the different types of wave behaviours?

• reflection: when waves bounce off an object

• transmission: when waves keep traveling in the same direction through an object

• refraction: when sound and light waves pass across a boundary between substances (air & glass), they change speed because the substances have different densities

• diffraction: when waves meet a gap in a barrier, they pass through the gap, they then spread back out after they pass through the gap

• scattering: when waves depart from the expected path and spread out in multiple directions

• absorption: when a wave (light or sound) enters a material and loses energy instead of passing through

what affects the speed at sound can travel?

temperature and air pressure

what’s the relationship between the distance the particles and the speed at which sound travels?

the closer the particles lie, the faster sound is able to travel

• the more densely the particles are arranged, the faster sound travels

how does temperature affect the speed of sound?

• lower temperature = slower speed of sound

• higher temperature = faster speed of sound

what’s the formula that links speed, distance and time?

speed = distance / time

electromagnetic spectrum

electromagnetic transverse waves that travel at the speed of light

what are the different types of electromagnetic waves on the spectrum?

• radio waves: used for radio/tv, they are reflected off the ionosphere

• microwaves: used to heat up, make water molecules vibrate to generate heat

• infrared: first part of the spectrum that animals can detect

• visible: includes all the parts that make up a rainbow

• ultraviolet: exposure can cause cell damage leading to cancers or loss of sight

• x-rays and gamma rays: very high energy waves which pentrate matter easily

what are the properties of shorter wavelengths?

higher energy and higher frequency

what are the properties of longer wavelengths?

lower energy and lower frequency

• the angle of incidence is equal to the angle of reflection

how to draw a ray diagram?

what are the properties of refraction?

• if a light wave passes from a medium in which it’s moving faster to a medium in which it’s moving slower, then the light wave will bend towards the normal

• when ray passes from a medium where it’s slower to a medium where it’s faster, then the light wave reflects away from the normal

• has an angle of incidence and an angle of reflection, but the two angles ARE NOT equal to each other because they travel through different media

• no refraction occurs when the waves cross the boundary surface at a 90 degree angle, if this happens the rays continue in the same direction

what are some techniques used in a medical imaging?

• Infrared:

  • passive image technique

  • camera detects emitted IR

  • measures body temperature

  • can locate poor circulation in cooler limbs

  • can detect raised temperature of a tumours

  • zero risk to patient or user

• X-rays:

  • can show images of skeletons and soft tissue

  • images stored on film or digitally

  • CT scans can show body in 3D

  • low risk to patient but high risk to radiographers

  • unsuitable for pregnant females unless baby is shielded

• Gamma rays:

  • patient injected with short half-life radioactive drug

  • location of radiochemical detected by gamma ray scanner

  • can target key organs for cleaner imaging

  • medium risk to patient and higher risk to clinicians

• Radio waves(MRI):

  • high quality 3D images of body

  • high frequency radio waves

  • strong magnetic field

  • low risk to patient and clinician

• Ultrasound:

  • only non electromagnetic imaging method

  • uses ultrasound which can travel into soft tissue

  • sound echo at density boundaries shows images of organs

  • can be done in real time

  • safe for neonatal scanning

  • very low risk

  • low resolution images