Mechanics Flashcards
Moments
Moment = force x perpendicular distance along the line of action about the pivot
Velocity
Velocity = change in distance/ change in time
Acceleration
Acceleration = change in velocity/ change in time
SUVAT
S = Displacement U = Initial velocity V = Final velocity A = Acceleration T = Time
Newtons first law
The velocity of an object will not change unless a resultant force acts on it
Newtons second law
The acceleration of an object is proportional to the resultant force acting on it.
F = ma
Newtons third law
If an object “A” exerts a force on object “B”, then object B exerts an equal but opposite force on object B
suvat (v)
v = u +at
suvat (s₁)
s = ut + ½at²
suvat (v²)
v² = u² + 2as
suvat (s₂)
(v + u)t / 2
Time (up)
2Uᵧ/a
Time (suicide)
√2Sᵧ
/a
Range (up)
Uₓt
Range (suicide)
Uₓt
Max height (up)
Uᵧ²
/2a
Final speed (suicide)
√Uₓ²+(at)²
Principle of Moments
For a body to be in equilibrium the sum of the clockwise moments about any point equals the sum of the anticlockwise moments about the same point
What is a couple
A pair of forces of equal size which act parallel to each other but in opposite directions. Causes a turning effect (a moment)
What is freefall
Where there is gravity acting on object and nothing else
Why do all objects fall at the same speed in a vacuum
f = ma
the only force acting is weight so W = mg
ma = mg (m cancels out)
a = g
Equations of motion in freefall
v = gt v² = 2gs s = 1/2gt² s = vt/2
What is terminal velocity
Terminal velocity happens when frictional forces equal the driving force
Momentum
m x v
linear momentum is always conserved
momentum before = momentum after
