P2.2 Flashcards
what are the 3 equations of motion?
v= u + at
s= 1/2 (u+v) x t
v^2= u^2 + 2as
newtons first law
an object stays at rest or moves with constant velocity unless a force acts on it
newtons second law
force = mass x acceleration
newtons third law
for every action there is an equal and opposite reaction
what is mommentum?
a quality of motion, it depends on the objects mass and velocity- it’s a vector quantity
equation for momentum
momentum= mass x velocity
equation for momentum
momentum= mass x velocity
what is momentum measured in?
kgm/s
law of conservation of momentum
the total momentum before an event is the same as the total momentum after
elastic collisions
momentum is conserved but KE isn’t
what is work done?
a transfer of energy
what are forces?
forces are pushes or pulls in a particular direction and can change the motion or shape of an object
name contact forces
-friction
-air resistance
-water resistance
-upthrust lift
-normal contact force
name non-contact forces
-gravity
-electricity
-magnetic
what is a resultant force?
when objects have several forces acting on them they can be seen as having one resultant force
free body diagrams
-arrows indicate forces
-size of arrow = size of force
-direction of arrow = direction of force
-draw arrows through center of mass
describe a skydivers drop
- weight > air resistance (unbalanced acceleration)
- weight = air resistance (balanced constant speed)
- open parachute- weight < air resistance (unbalanced deceleration)
- weight = air resistance (balanced constant speed)
equation for work done
work done= force x distance in direction
what is work done measured in?
Joules
what is power?
power is the rate at which work is done
equation for power
power= work done / time
what is power measured in?
Watts
