Mechanics (topic 2) Flashcards
If v is constant
No acceleration
Free body diagram
Add up all the vectors to figure out the net force (Fnet)
**If Fnet = 0, then no acceleration (equilibrium) but can still be moving!!! ex. plane
Newton’s 1st Law
An object in rest stays in rest, unless acted on by an external, unbalanced force. An object in motion tends to stay in motion.
Newton’s 2nd Law
Force = mass x acceleration
Newton’s 3rd Law
Every action has an equal and opposite reaction
Coefficient of static friction
Ff ≤ μs R
where,
Ff = friction force (N)
μ = coefficient of friction
R = reaction force (N) also called normal force
Coefficient of dynamic friction
Ff = μd R
where,
Ff = friction force (N)
μ = coefficient of friction
R = reaction force (N) also called normal force
Work equation
W = Fs cos θ
where,
W = work done (J)
F = applied force (N)
s = displacement (m)
θ = angle between force and displacement (°)
Kinetic energy
Ek = 1/2 mv^2
where,
Ek = kinetic energy (J)
m = mass
v = velocity
Potential energy (spring)
Ep = 1/2 k Δx^2
where,
Ep = potential energy (J)
k = spring constant
x = displacement from equilibrium
Potential energy (gravitational)
Ep = mgh
where,
Ep = potential energy (J)
m = mass
g = gravity
h = height
Total energy
Sum of Ek and Ep
Total energy is conserved, meaning constant
Power
P = Fv
P = power (watts)
F = Newtons
v = ms^-1
**Power = energy / time
Momentum
p = mv
where,
p = momentum (kgms^-1)
m = mass (kg)
v = velocity (ms^-1)
**momentum is conserved
Frictional coefficient and normal force on exam
Draw the diagram to make it easier
