Defintions and equations Flashcards
Define Displacement
Distance in a given direction
What is the equation for Displacement
s = v x t
displacement = velocity x time
Define velocity
The rate of change of displacement
What is the equation for Velocity
v = Δ s / Δ t
velocity = change in displacement / change in time
Define Acceleration
Rate of change of velocity
What is the equation for Acceleration
a = Δ v / Δ t
acceleration = change in velocity / change in time
Define Current
The rate of flow of Charge
What is the equation for Current
I = Δ Q / Δ t
current = change in charge / change in time
Define the Coulomb
1 Coulomb is the charge that crosses a section of circuit in 1 second when a current of 1 amp flows
Which direction does Conventional Current flow
From positive (+) to negative (-)
Which direction do electrons flow
From negative (-) to positive (+)
What is the equation for current in a material
I = nAve
current = free electron density x cross-sectional area x electron drift velocity x charge
Define Voltage
Voltage is the energy transferred per coulomb of charge (The number of joules transferred per coulomb of charge)
What is the equation for Voltage
V = W / Q
voltage = energy / charge
Define Resistance
The ratio of potential difference to current
What is the equation for Resistance
R = V / I
resistance = voltage / current
Define Ohm’s Law
Provided the temperature is consistent, the Voltage (V) across something is proportional to the Current (I) through it
Define “a negative temperature coefficient of resistance”.
This is when the resistance of a component decreases with temperature
Define “a positive temperature coefficient of resistance”.
When a component’s resistance increases with its temperature
What is the SUVAT equation that links v, u, a and t?
v = u + at
What is the SUVAT equation that links v, u, a and s?
v^2 = u^2 + 2as
What is the SUVAT equation that links s, u, t and a?
s = ut + (1/2)at^2
What is the SUVAT equation that links s, u, v and t?
s = (1/2)(u + v)t
When using SUVAT, what does each letter mean?
S - Displacement, m
U - Initial Velocity, ms^-1
V - Final Velocity, ms^-1
A - Acceleration, ms^-2
T - Time, s
What is the equation that links both graphing intercepts and the gradient?
y = mx + c
Y-Intercept = Gradient(x) + X-Intercept
Define Moment
The force multiplied by the perpendicular distance from line of action of force, to pivot point
What is the equation for Moment?
moment = force x perpendicular distance to pivot
moment = F x d
Define Torque
The rotational motion when two equal forces act in opposite directions
What is the equation for Torque?
torque of a couple = force x perpendicular distance between the forces
t = F x d
Define A Couple
The pair of equal, parallel forces which act in opposite directions to produce rotational motion only
Define Mass
The property of a body which resists change in velocity
Define Weight
The force that acts upon a mass due to a gravitational influence
What is the equation for Weight?
weight = mass x gravitational field strength
w = m x g
Define Equilibrium
When the resultant forces/moment acting on an object are 0 on all axis
Define 1 Newton
The force required to give a mass of 1kg an acceleration of 1ms^-2
What is the secondary equation for calculating the resistance of two objects in parallel?
R(t) = R(1) x R(2) / R(1) + R(2)
Define The Centre of Gravity
The point at which the weight of an object acts