PHYSICS OMG IM GONNA DIE

What is frequency?

Cycles per second

What is the period?

Cycles per second

What is the wavelength?

The distance between two consecutive points on successive waves

How do you calculate the period?

1/frequency

If the frequency of a wave is 8 Hz, then how much of the wave passes in 1 second (period)?

1/8th (Inverse)

What does a displacement-time graph show?

The amplitude, frequency, and period of a wave

How do you calculate the velocity of a wave?

v=fλ

If there are 6 waves per minute, and the distance between each crest is 10m, how do you solve?

Frequency=6/60=0.1Hz
∴λ=0.1/1 = 10m

v=fλ
0.1×10 = 1m/s

What is the frequency of thsi wave?

Can’t tell. Time for one λ to occur is known, but the magnitude of λ is not

What is the frequency of this wave

Can’t tell. Magnitude of λ is known, frequency is not

How do you calculate frequency in these two graphs

Crest moves 4cm in 0.1 seconds. λ is known to be 8cm, so it takes 0.2 seconds to complete a full cycle. This is the period, so take the inverse (1/0.2), which = 5 Hz

What unit must wave velocity be in

Meters

What happens when a wave is transmitted through a more dense substance?

It is reflected underneath the axis, whilst a secondary smaller wave continues along the more dense medium

What happens when a wave is transmitted through a less dense substance?

It is reflected back normally, whilst a secondary larger wave continues along the less dense medium

What is the law of reflection?

θ_I=θ_r

What is the angle of incidence?

The incoming wave

What is the angle of reflection?

The reflected wave

What are standing waves

Waves that are stationary rather than travelling through a medium

What does a small gap do in terms of diffraction

Creates waves that have increasingly larger angles going away from the wall

What does a large gap do in terms of diffraction

Creates waves that have marginally larger angles going away from the wall

What does a small wavelength do in terms of diffraction

Creates waves that move almost in a straight line going away from the wall

What does diffraction at an edge do

Creates waves that somewhat curve back after the edge

What does diffraction around an obstacle do

The waves eventually close back in after going around the obstacle

What are vectors?

Quantities that contain magnitude AND direction (e.g. 5m/s North)

What are scalars?

Quantities that contain just magnitude (e.g. 5m/s)

How can vectors be symbolised?

F ˜F →F

How do you draw vector arrows?

What is distance?

The total length of the path travelled

What is displacement?

The shortest straight-line change in position from start to finish

How do you find distance?

Add path lengths

How do you find displacement

Find the magnitude of the quickest path (as well as direction)

How do you find average speed

DISTANCE CHANGE

How do you find average velocity?

DISPLACEMENT CHANGE

What does the gradient in a distance-time graph represent?

Speed

What does a negative gradient in a distance-time graph represent?

Returning/Going backward

How do you calculate velocity on a time-distance graph

Find the gradient

How do you calculate displacement on a velocity-time graph

Find the area underneath the curve

How do you calculate acceleration on a velocity-time graph

Find the gradient

How do you calculate acceleration?

How do you calculate displacement when something is dropped (gravity)?

What differences are there in the gravity/displacement formula when something is thrown upward

Acceleration is -9.8 m/s, initial velocity stays positive

What is the formula for Newton’s Second Law

What is Earth’s Gravity?

9.8m/s²

What does it mean for acceleration when something is moving at a constant speed?

a=0

Formula for frictional force?

F_f=F_a-F_net

Steps to find frictional force?

1. Use F_f=F_a-F_net

2. Determine F_a, m, a

3. Use F=ma to determine net force

   
   

Is momentum a scalar or a vector

Vector

What is the formula for momentum

p=mv

How do you find the total momentum of a system?

Find the total momentum of all objects and add together.

How do you find total change in momentum?

Use p=mv for different values, and find the difference.

How do you find impulse?

∆p=Ft

How do you determine impulse on a Force-time graph

Area under the curve

What is the law of conservation of mass?

That the amount of momentum in a system is always the same

What are elastic collisions?

When objects collide and bounce off of each other

What are inelastic collisions

When objects collide and remain bounded

What is work/mechanical work?

It is the force multiplied by the distance moved in the direction of force

What are the two types of mechanical energy?

Potential and Kinetic

What is kinetic energy?

The energy an object has when it is moving

What is the law of conservation of energy

Energy cannot be created nor destroyed

How do you calculated work done?

W=FD (Force x distance)

How do you calculate work done on a force-displacement graph

Area under the curve

What is the formula for Kinetic Energy?

What is the formula for Gravitational Potential Energy?

How do you interpret and energy-time graph?

xyz

What is the period in terms of frequency

1/frequency

What’s the amplitude?

The height from the origin

What is diffraction

When waves bend behind a barrier or the wavefront is broken up into many smaller pieces

What is polarisation

When light has been filtered so it only vibrates in one single direction

What is superposition

The resulting wave when multiple waves collide

How do you draw superposition

Add the y coordinates of each wave and draw at that point

What is resonance

The frequency of an outside push that creates the biggest wave

What is natural frequency

The normal speed at which a disturbed object moves/vibrates

What part of a wave is this?

Crest

What part of the wave is this

Trough

What is

What part of the wave is this

Amplitude

What is this?

Plane Wavefront

What is this?

Circular Wavefront

What are the two ways waves can transfer energy?

Transverse or longtitudinal

What is frequency?

Cycles per second

What is period?

Seconds per cycle

What is a rarefaction?

The point in a longitudinal wave when the particles are the furthest

What is reflection?

Where the incoming wave hits a surface and bounds back into the original medium

What is the law of reflection?

Where angle of incidence equals the angle of reflection

What is refraction

When an incoming wave passes through a boundary into a medium usually of a different density

How do you find the speed of sound in air?

v=v₀°c + 0.6T

How do you find the frequency of a sound wave in a medium?

ƒ=v/λ