Forces in Motion Definitions Flashcards
Newton’s 1st Law
an object remains at rest or in uniform motion unless acted on by a resultant force
Newton’s 2nd Law
the rate of change of momentum of an object is proportional to the resultant force on it - takes place in the direction of the force (F=ma)
Newton’s 3rd Law
if object A exerts a force on object B, then object B will exert an equal and opposite force on object A
Principle of Conservation of Energy
energy is neither created not destroyed, only converted (transferred) from one source to another
Energy conversions of an object falling in presence of resistive forces
loss in GPE = gain in EK + work done against resistive work done typically appears as heat
Terminal Velocity
Where drag=mg, travelling at a constant velocity, no acceleration.
Drag / Air Resistance ATMOSPHERIC
Comes from the friction from air molecules in the atmosphere.
Work Done Definition
force multiplied by distance moved in the direction of the force
Work Done Units
SCALAR Joules
Power
rate at which energy is transferred (energy transferred aka work done / time taken)
Power Units
SCALAR Watts Js^-1
Force (momentum change)
force = rate of change of momentum
VECTOR
Momentum Units
kgms^-1
Momentum
Mass x Velocity
Rate of Change of Momentum Units
kgms^-2
Impulse
VECTOR
force x time (FchangeinT)
Impulse = change of momentum
Impulse Units
Ns
kgms^-1
Area under a graph of force against time
change in momentum / ImpulseP
Principle of conservation of linear momentum
in a collision the total momentum before equals the total momentum after, providing no external forces are acting
Elastic Collision
collision where kinetic energy is conserved
Inelastic Collision
collision where kinetic kinetic is not conserved
