Kinematics Flashcards
When can u re-arrange arrows to make a triangle
When they are all acting on the same object with a resultant force of 0
Sin
= opp/hyp
Cos
= Adj/hyp
Tan
= Opp/adj
For a system in equilibrium:
Resultant force = 0
Resultant moment = 0
F =
F = ma
KE =
KE = 1/2 mv^2
What is the force acting downwards
Weight
Closed triangle means
Resultant force is 0
Newton’s first law
An object will remain at a constant velocity unless acted on by a resultant force
Newton’s second law
F = ma
Newton’s 3rd law
Every action has an equal and opposite reaction
Scalars are
Quantity’s with only magnitude and NO direction
Vectors are
Quantity’s with both magnitude and direction
Value of g
-9.81
Distance vs displacement
Distance has no direction whilst displacement has direction (say compass direction or angle for displacement)
Suvat equation without S (displacement)
V = u + at
Suvat equation without t (time)
V^2 = u^2 + 2as
Suvat equation without v (final velocity)
S = ut + 1/2 at^2
Suvat equation without u (initial velocity)
S = vt -1/2 at^2
Suvat equation without a (acceleration)
S = 1/2 (u+v) t
Uncertainty
Half range
Percentage uncertainty
Uncertainty / average
Weight
Y
X
Weight = mg
Y = mg cos(ø) = R (normal reaction force)
X = mg sin(ø) = Fthrust = ma = friction (at equilibrium)
Friction =
Friction = /M R
Friction = coefficient of friction * normal reaction force
Resultant force =
And therefore
Fthrust - friction
a = g sin(ø) - (/M)g cos(ø)
Most important thing
Draw labelled diagrams
Don’t forget to convert
Kg to N by * by 9.81
