Please enable JavaScript.
Coggle requires JavaScript to display documents.
p2 (momentum (momentum = mass x velocity, when a resultant force acts on…
p2
momentum
-
when a resultant force acts on an object for a certain time, it cause a change in momentum
-
-
-
-
faster a change happens, the bigger the force causing it
friction
-
-
if driving force is equal to friction, object will move at steady speed
if driving force is greater than friction, accelerates
occurs between two surfaces in contact and drag occurs when object passes through a fluid, eg air resistance
newton's third law
when two objects interact, forces they exert on each other are equal and opposite
when skater a pushes on skater b, she feels an equal and opposite force from skater b's hand
both feel the same sized force and accelerate away from each other
-
when a book is on a table, weight of book is pulled down by gravity and the book pulls back up on the earth
normal contact force from the table pushing up on the book and the normal contact force from the book pushing down on the table
work done
when a force makes an object move, energy is transferred and work is done
effort needs a supply of energy from fuel, food, electricity etc
moves object and transfers recieved energy to other stores
-
force applied to move object, work done will equal energy transferred to the kinetic energy store
if object is already moving, force slows it and energy transferred from the object's energy store is equal to the work done against the object's motion
work done on lifting an object equals energy transferred to the gravitational potential energy store
terminal velocity
resistance is directly proportional to velocity of the object, as velocity increases, resistance increases
gradually reduces acceleration until friction is equal to the driving force so it stops acceleration
forces a balanced, will have reached maximum velocity/terminal velocity
a skydiver accelerates as weight due to gravity > air resistance
air resistance increases as velocity increases until
weight = air resistance, reach terminal velocity
parachute opens and weight < air resistance so they decelerate
as velocity decreases, air resistance, air resistance also decreases until weight = air resistance and they reach new terminal velocity
inertia
-
dependent on the mass of the object, larger mass, larger inertia and harder it is the change velocity
larger mass required more force to accelerate by a certain amount, so larger inertia
conservation of momentum
in a collision when no other external forces act, momentum is conserved
-
if a red ball hit a yellow one, with the same mass, the red ball stops and the yellow ball has the same velocity as the original velocity of the red ball
gravity
bigger things have greater gravitational field
earth has a gravitational field that pulls everything towards it
moon's gravitational field creates tides on earth
value of about 10N/kg, anything dropped moves at 10m/s^2
-
collisions
elastic, total energy in the kinetic energy stores of the objects colliding is the same before and after
kinetic energy store conserved
inelastic, some energy in the kinetic energy stores is transferred to other stores
eg heating or sound
drag
greater drag, lower terminal velocity, drag depends on object's shape and area
with open parachute there is more air resistance because area is larger, but driving force is the same
terminal velocity is much smaller
-
-