Work And Energy Flashcards
What is needed to do work
What is it measured in
Energy
Energy and work are measured in joules (J)
What factors does the amount of work done depend on
The size of the force in newtons (N)
The distance the object is moved in metres in the direction of the force
What is power a measure of
What is the unit of power
Power measures how quickly work is done; the work done per second
Measured in watts (W)
What is kinetic energy
The energy an object has because of it’s movement
Measured in joules
What does kinetic energy depend on
The mass of the object (kg)
The speed on the object (m/s)
What is a disadvantage to biodiesel
Plants that are used to make it are grown in fields that could be used to grow food
What is the trouble with cars powered by electricity
Batteries are charged using electricity generated in power stations that does pollute
Why have aerodynamic cars got lower fuel consumption
Less wind resistance
What needs more work
A small force for a short distance
A big force for a short distance
A big force for a short distance
What needs more work
A big force for a short distance
A big force for a long distance
A big force for a long distance
What is momentum
The measure if an object’s tendency to move in a straight line with constant speed
How can air resistance (drag) increase
More speed
More surface area
At terminal velocity (speed) what two things are equal
Weight=drag
Explain terminal velocity for falling object
It cannot get any faster, falls at constant speed
The forces bare balanced
Air resistance is equal to the weight of the object
Why is there less air resistance higher up in the atmosphere
There are less air molecules therefore less air resistance
They don’t collide as often as there are fewer
For a falling object what happens when the weight is bigger than the air resistance
Falling object speeds up
For a falling object what happens when the air resistance is bigger than the weight
The falling object slows down
What kind of object (shape and speed) will have the most drag
More drag on an object with larger surface area and on a faster object
What is gravitational potential energy
The energy an object has due to its position in the earth’s gravitational field
Who has more gravitational potential energy and why
A person on a low diving board
A person in a high diving board
A person in a high diving board
He is further away from the ground
Who has more gravitational potential energy and why
A light person on a diving board
A heavy person on the same diving board
A heavy person
They have more mass
When an object falls describe the energy transfer as it gets closer to the ground
An object’s kinetic energy increases (it gets faster) as its gravitational potential energy reduces (it gets closer to the ground)
GPE has been transferred into KE
If mass of falling object is doubled the kinetic energy..
Doubles
Is speed of falling object is doubled, the kinetic energy…
Quadruples
When an object is falling at terminal speed the what happens to speed and kinetic energy (do they change?)
speed does NOT change so kinetic energy does not increase
For a skydiver, why does gravitational potential energy decrese
It is being transferred to surrounding air particles through friction (heat) sound energy etc
Does gravitational potential energy increase/decrease when an apple falls tree
GPE decreases
Does gravitational potential energy increase/decrease when air craft flies horizontally
GPE remains constant
Does gravitational potential energy increase/decrease when a rocket is fired
GPE increases
When is work done
What is developed
When a force moves an object in the direction in which the force acts
Power is developed
