Motion and Energy Flashcards
Newtons 1st law
a stationary object will be at rest or a moving object will travel at an constant velocity (also in same direction) unless acted upon by a resultant force
if an object moves at constant speed resultant force must = 0
Newtons 2nd law
F=ma
the resultant force F is equal to mass x acceleration
formula for momentum
mass x velocity
conservation of momentum
momentum before = momentum after
impulse
mv- mu
v=final velocity
u=initial velocity
force (in terms of momentum)
rate of change of momentum ie. impulse/time
free fall acceleration (terminal velocity)
when an object is falling air resistance and gravity act on it
terminal velocity is the point where the resultant force = 0 (air resistance and gravity are equal) and is the max velocity an object can reach
ma=mg therefore a=g
g is taken to be 10ms^-2
weight
the force due to gravity, W=mg
Newtons 3rd law
for every action there is an equal and opposite reaction
formula for power
power measured in watts
force x velocity
energy transfer(work done)/time
work done
force x distance
measured in joules
also the loss of kinetic energy (energy transfered)
kinetic energy formula
1/2mv^2
potential energy
mgh
conservation of energy
energy cannot be created or destroyed, can only be transfered
mechanical energy: when no forces other than gravity do work on an object the change in KE= change in PE
work energy principle
change in total energy = work done
