2. Mechanics Flashcards
What are the equations of motion / suvat equations?
s=((u+v)/2)t
s=ut+1/2at^2
v=u+at
v^2=u^2+2as
What is suvat?
We use suvat when an object is moving at uniform acceleration
s=displacement(m)
u=initial velocity(ms^-1)
v=final velocity(ms^-1)
a=acceleration(ms^-2)
t=time(s)
What is instantaneous velocity?
The velocity of an object in a specific point in time (instantaneous)
How does an acceleration time graph work?
Represent the change in velocity overtime
area under graph = change in velocity
What is uniform acceleration?
where acceleration is constant
What’s the difference between scalar and vector?
Scalar gives 1 piece of info
no direction, just magnitude
E.g distance, speed, mass
Vector gives 2 pieces of info
has a direction and magnitude
E.g displacement, velocity, weight
What is resolving a vector?
splitting it into it’s horizontal and vertical components
What does it mean when an object is described as uniform?
It’s centre of gravity is exactly at the centre
So its weight is counted from exactly the centre
What’s Newton’s 1st Law?
A body will remain at rest or constant v if no force is being acted on it
Needs a resultant force on object to move
What’s Newton’s 2nd Law?
The acceleration of a body is proportional to the resultant force
So acceleration is in the same direction as the force
f=ma
What’s Newton’s 3rd Law?
When body A exerts a force on body B, body B exerts an equal opposite force on body A
It must be a reaction between the 2 bodies
This has to happen as they are in equilibrium
Has to be same type of force
E.g the table exerts an equal and opposite force on the mac
What are moments?
A moment is a ‘turning force’
Moment(Nm)=force(N) x perpendicular distance from pivot(m)
M=Fxd
This makes moments acting clockwise and anticlockwise
What’s the principle of moments in angles?
Σ clockwise moments = Σ anticlockwise moments
for equilibrium
What happens when there’s several moments?
If in equilibrium, and there’s 1 clockwise and 2 anticlockwise moments:
M(1)=M(2)+M(3)
w(1)d(1)=w(2)d(2)+w(3)d(3)
What is the conservation of energy?
Energy can never be lost or gained out of nowhere
- only through transfers
