M2 Dynamics Flashcards
action force
the force acting on a body
balanced forces
when forces combine to cancel each other out
conservation of energy
energy cannot be created nor destroyed, only transformed from one form to another
conservation of momentum
when two or more objects interact, the total momentum is conserved if no external forces act
contact force
a force acting when objects are in physical contact
density (kg m⁻³)
mass of a substance per unit volume
- density = mass/volume
dynamics
the study of the motion of objects and the forces acting on them
elastic collision
a collision in which objects rebound with no deformation, change of shape, or production of heat. Both momentum and kinetic energy are conserved.
Σmv before = Σmv after
Σ1/2 mv² before = Σ1/2 mv² after
energy
the property of a system that enables it to do work
- scalar quantity (J)
equilibrium
the state of an object when not acted upon by a net force
- may be at rest or travelling at a constant velocity
impulse
the change in momentum of an object
- Impulse = F x t (Ns)
- Impulse = m(v-u)
inelastic collision
a collision in which momentum is conserved but kinetic energy is lost
Σmv before = Σmv after
inertia
the resistance of an object to a change in its motion
kinetic energy
the energy of an object due to its motion
Eₖ = 1/2 mv²
mass
the amount of matter in an object (kg)
mechanical energy
kinetic or potential or heat energy
momentum
“mass in motion”
p = mv (Ns)
net force
a single force that presents all the forces acting on a body
Newton
the unit of force that will give a mass of 1kg an acceleration of 1ms⁻²
N1L (inertia)
Every object continues in its state of rest or uniform motion in a straight line, unless acted on by an unbalanced force
N2L (net force)
F=ma (net force)
N3L
Every action force has an equal and opposite reaction force
1. the forces acting on different objects
2. same type of force
N3L force pair: force of A on B
force of B on A
3. Equal in magnitude, opposite in direction
☆ forces are equal in magnitude, but the EFFECT could be drastically different
potential energy
the energy stored in an object due to its position, its shape or its state
power
the rate of change of energy (Watts)
- scalar quantity
reaction force
an equal and opposite force exerted by a body against a force acting upon it
resultant force
the vector addition of all the forces acting
tension
the force in a string connected to a mass
terminal velocity
the final velocity reached by an object when the resistance force is equal and opposite to the weight force
unbalanced forces
produce acceleration/deceleration
weight
the force due to gravity on an object
F = mg
work
energy required to make an object change its position
- scalar quantity (J)
W = net Force x displacement
W = Fs
W = ΔEₖ = 1/2 mv² - 1/2 mu² (final minus initial)
classifying forces into
contact or non-contact (field)
INCLINE PLANES
weight force is broken down into
force down the plane (F = mg sinθ)
force perpendicular to plane (F = mg cosθ)
FORCE PAIRS
+ down the plane & friction
+ reaction/normal force (F = mg cosθ)
change in GPE in a uniform field (formula)
ΔU = mgh (also = work)
power (formula) and more
P = Fv
P = W/t
W = change in energy
Power is a measure of how difficult it is to do work (If you can spread the work over a longer time, then you need to use less power)
kinetic energy (Eₖ) formula
1/2 mv²
Impulse ♡
Impulse is used to quantify the impact that force has on an object over a period of time
Impulse = Ft
Impulse = m(v-u) = Δp (change in momentum)
units Ns
- vector quantity
