Energy transfer Flashcards
The faster you’re going the ……… the breaking force needed to stop you
bigger
What is stopping distance made up of?
Thinking and breaking distance, from when the driver sees the hazard to when the car stops moving completely
What is the breaking distance affected by?
How fast you’re going
How dopey you are - drugs, tiredness, alcohol or a careless attitude affects this
What external factors reduce the stopping distance?
Bad visibility like rain or bright lights so the time the driver has to break is shortened as they don’t see the hazard
What four factors affect breaking distance?
How fast you’re going - faster the further it takes to stop
Quality of breaks - worn will take longer to effectively slow you down
Tyre quality - a minimum tread depth of 1.6mm is needed to get rid of water, debris can cause skidding
How good the grip is - depending on road surface, weather conditions, tyres
What is the definition for work done?
When a force moves an object through a distance, energy is transferred and work is done.
Whenever something moves something else is providing some sort of …. to …. it.
The thing putting in the effort needs a supply of ….
It then does ….. by moving the object, so it ….. the energy it ….. as fuel, into other …… .
Wasted or ……, the energy transferred is still ………. ……
effort to move it
energy
work, transfers, receives, forms
used, work done
What is the formula for work done?
Work done (J) = force (N) X distance (m) W of FxD in a triangle form
What is gravitational potential energy?
What is the equation?
The energy an object has because of its vertical position in a gravitational field
GPEnergy (J) = mass x g x height
What happens when an object is raised vertically? (2 ish)
Work is done against the force of gravity, and the object gains GPEnergy
What is the gravitational field strength on the planet?
10Nkg
What is kinetic energy?
What is the equation?
The energy an object has when it is moving
KE = 1/2 X mass X speed-squared
Kinetic energy depends on the …. and … of the object.
The more it … the ….. it will go, so the …. it’s … energy will be.
mass , speed
weighs, faster, bigger it’s kinetic
Kinetic energy transferred is ….
When a car is moving it has ….
What has to happen to this energy when a car needs slowing down?
So the …. energy is ……. into ….. energy and …. between the wheels and the break pads, causing the ….. of the … to increase.
work done
kinetic energy
it needs to be converted into other types, due to conservation
kinetic, converted, heat, friction, temperature, breaks
Kinetic Energy Transferred =
1/2 X M X Vsquared =
Work done by brakes F x d m is mass of car in kg v is speed of car in m/s f is maximum breaking force in N d is breaking distance in meters
What happens to an object’s potential energy when it falls?
It’s converted into kinetic energy, heat or sound
The further it falls the faster it goes
What is the equation for the potential energy lost that’s transferred into kinetic energy?
K energy gained= Potential energy lost
What do some meteors and space shuttle shave when they enter the earth’s atmosphere?
What happens to some of their kinetic energy when they enter, why and what is done?
What happens due to to friction?
They have a very high kinetic energy
Friction due to collisions with particles transfers the energy into heat and work is done.
The temps can be so extreme that meteors burn up before they hit the earth
What are meteorites?
The meteors that can make it to the earth’s surface
How are space shuttles made so that they don’t burn up in the atmosphere?
They have heat shields made from special materials which lose heat quickly allowing the shuttle to reenter.
Elastic objects store energy as …..
elastic potential energy
When you apply a force to an object you cause it to ……. and …… … …….
Any object that can go back to its original shape after the force has been removed is an …….. …….
stretch and change in shape
elastic object
What is done to an elastic object to change its shape?
The energy is not …. by the object but …. as ….. ….. ….. .
Work
lost, stored as elastic potential energy
Elastic potential energy is then converted into …. ….. when a force is removed from an elastic object.
So the object ….
kinetic energy
returns to its original shape
The extension, e, of a …. spring is …. …… to force applied, F.
The extension is measure in ….. , and the the force is measure in …
stretched spring, directly proportional
meters
newtons
What is the equation for spring extension?
What do the letters mean?
F= K x e
F is force, K is the spring constant, e is the extension, m
What does the spring constant value depend on?
What is it measured in?
The material being stretched
Newtons per meter, N/m
But what stops the direct proportion between the spring and force?
When the force gets too big, past the limit of proportionality, the material will be permanently stretched. When the force is removed the material will be longer.
Describe the graph showing force (y axis) against extension (x axis), so the shape of the curve….
What is P?
It rises in a straight line then at point P the line curves so the force isn’t proportional to the extension
P is where the object is under the maximum force where it can still extend proportionally, the limit of proportionality.
