P 4. Energy Concepts Revamp Flashcards by Shirou Aizen

Define work
(2-way + 2 things)

Product of force and distance moved in direction of force
when force is constant
Scalar quantity
Measured in Joules (J)

How well did you know this?

Not at all

Perfectly

Work done expressed in a formula?

Work done = force x distance

How well did you know this?

Not at all

Perfectly

Work done formula expressed in symbols?

J = N x m

How well did you know this?

Not at all

Perfectly

Define J
(Work done formula)

Joules
(J)

How well did you know this?

Not at all

Perfectly

Define N
(Work done formula)

Newtons
(N)

How well did you know this?

Not at all

Perfectly

Define m
(Work done formula)

Metres
(m)

How well did you know this?

Not at all

Perfectly

Define energy
(3 things)

The ability to do work
Scalar quantity
Measured in Joules (J)

How well did you know this?

Not at all

Perfectly

1J is the….?
(The joule in the work done formula)
(3-way)

work done when
a Force of 1N moves its point of application
1m in the direction of that Force

How well did you know this?

Not at all

Perfectly

1J = ?

1 Nm

How well did you know this?

Not at all

Perfectly

1J in base units?
(3 steps)

F = ma
= kgms^-2
1kgm^-2s^-2

How well did you know this?

Not at all

Perfectly

Show an equation is homogeneous?

If the case calls

How well did you know this?

Not at all

Perfectly

What are the 2 formulas for work done?
(1 of them is in the data booklet)

W = Fx
W = Fxcosθ

How well did you know this?

Not at all

Perfectly

Explain work done = energy
(2 things + 2-way)

Work be done moving an object
Same with stopping an object
Energy at start transferred to work done stopping object
when it comes to rest (at ground level)

How well did you know this?

Not at all

Perfectly

What’s the jig with “ground level” with work done = energy?
(2 things)

Object may still have GPE (E_p)
if not at ground level

How well did you know this?

Not at all

Perfectly

What is the work energy relationship?

When object slows/speeds up
work being done on object

How well did you know this?

Not at all

Perfectly

How do u find the work done from object slowing/speeding up?
(3-way)

Difference in the initial,
and final kinetic energies
of the object

How well did you know this?

Not at all

Perfectly

How do u find the braking force acting on an object?
(2 things)

Use W = F x D
Rearrange for F

How well did you know this?

Not at all

Perfectly

What does it mean if “total energy is conserved even though there is a loss in kinetic energy”?
(2-way)

Work done slowing the car
is transferred to thermal energy

How well did you know this?

Not at all

Perfectly

Work = change in Kinetic energy expressed as in symbols?
(It’s in data booklet)

Fx = ½mv² - ½mu²

How well did you know this?

Not at all

Perfectly

What’s Fx = ½mv² - ½mu² used for?

Finding the kinetic energy at the end of journey

How well did you know this?

Not at all

Perfectly

How do u find the average resistive force?
(5 ways, step by step)

Use equation to find GPE
GPE = KE + wd against friction
Rearrange for wd
Then W = FD
Rearrange for F

How well did you know this?

Not at all

Perfectly

What is kinetic energy?
(2-way)

The energy possessed
by a moving object

How well did you know this?

Not at all

Perfectly

What’s the equation to find kinetic energy?
(In data booklet)

E_k = ½mv²

How well did you know this?

Not at all

Perfectly

KE equation expressed in words?

Kinetic energy = ½ x mass x speed²

How well did you know this?

Not at all

Perfectly

Define E_k? (KE equation)

Joules (J)

Define m (KE equation)

Mass (kg)

Define v (KE equation)

Velocity (ms^-1)

What is Gravitational potential energy? (E_p) (3-way)

- Energy possessed by an object - due to its position - or height about the Earth

What's the equation to find gravitational potential energy? (In data booklet)

E_p = mgh

GPE equation expressed in words?

Gravitational energy = mass x gravitational field strength x height

Define E_p? (GPE equation)

Joules (J)

Define m (GPE equation)

Mass (kg)

Define g (In data booklet) (GPE equation)

Gravity (9.81ms^-2)

Define h (GPE equation)

Height (m)

How to derive GPE? (4-way)

- Wd = f x d - f = ma - Moving thru air ∴ a = g - Wd = m x g x h

What is elastic potential energy? (4-way)

- Potential energy stored - as a result of deformation - of an elastic object - aka stretching of a spring

Define an "elastic object"? (2 things)

- Can become as it was - return from deformation

How to find EPE of a wire?

EPE = ½Fx

Define F (EPE equation)

Average force (N)

Define x (EPE equation)

Extension (m)

But what happens if u sub in force against extension gradient in EPE equation?

U get work done needed to stretch a spring

How to find the work done needed to stretch a spring?

Work = ΔPE = ½kx²

Define k (Wd needed to stretch a spring)

Spring constant (k...)

Define x (Wd needed to stretch a spring)

Distance the stretch of the spring is (m)

When talking about the conservation of energy of an object, what must be considered? (3 things)

- Changes in kinetic energy - Changes in gravitational energy - When to state it's max or zero energy

A ball is being thrown up, explain point A (2 things)

- KE decreases, GPE increases - KE > GPE

A ball is being thrown up, explain point B (2 things)

- KE decreases, GPE increases - GPE > KE

A ball is being thrown up, explain point C (2 things)

- KE = zero - GPE = max

A ball is being thrown up, explain point D (2 things)

- GPE decreases, KE increases - GPE > KE

A ball is being thrown up, explain point E (2 things)

- GPE decreases, KE increases - KE > GPE

When ball being thrown up, how come at point C the KE is zero? (3 things)

- Object at its highest point - Briefly has zero velocity - Therefore zero KE

What does the conservation of energy in a system tell us?

Initial energy for a system = final energy for a system

How do u work out energy lost due to friction? (2 possible methods)

KE = GPE + heat + sound GPE = KE + heat + sound

How to find force/distance of energy lost due to friction? (2-way)

- Heat + sound = work done (W_f) - W_f = Fx

Define power (3 things)

- The rate of doing Work - Scalar quantity - Measured in watts (W) or Js^-1

1 Watt = ?

1Js^-1

1Js^-1 = ?

The equation for power? (In data booklet)

P = W/t

Define w (Power equation)

Energy (J)

Define t (Power equation)

Seconds (s)

What's the "better" power equation? (Not in data booklet)

P = Fv

Define F ("better" power equation)

Force (N)

Define v ("better" power equation)

Velocity (ms^-1

Show how fv = w/t is homogenous (4-way)

1. fv = w/t 2. maD/t = ½mv²/t 3. kgms^-2ms^-1 = kgm²s^-2s^-1 4. kgm²s^-3 = kgm²s^-3

What's the FIRST way to find efficiency %?

% Efficiency = (useful energy output/total energy input) x 100%

What's the SECOND way to find efficiency &?

& Efficiency = (useful power output/total power input) x 100%

What are Sankey diagrams used for?

- Show efficiency - by which the width of the arrow - is the % of energy

Define the conservation of energy? (5-way B|)

- Energy cannot be created or destroyed - just transferred from one form - to another - or transferred from one place - to another

What is chemical energy? (2-way + 1 thing)

- Energy stored in mixtures of chemicals - or in chemical compounds e.g. All fuels (coal, oil, gas) store chemical energy (potential)

What is electrical energy? (3-way)

- Energy transferred in electrical circuits - by the motion of charger carriers - such as electrons (kinetic)

What is radiant energy? (2 things)

- Energy carried by all types of electromagnetic waves - i.e. electromagnetic spectrum n stuff (kinetic)

What is internal energy? (4-way) (Very familiar)

- Energy possessed by a body due to - the random distribution of - **kinetic and potential energies** - of the molecules which make it up

What is thermal/heat energy

Energy due to temperature of an object (kinetic)

What is sound energy? (2 things)

- Energy produced by vibrating objects e.g. musical instruments, speakers

Past paper questions shall be there