Unit 8 & 9 Energy - Forces Doing Work/ Forces and their Effects Flashcards
When is energy transferred?
Whenever things happen
What are the energy transfers for a light bulb?
Electricity transfers energy to an electric light bulb, which transfers the energy to the surrounding by light and heating.
What is the word equation for work done?
Work done (J) = force (N) x distance in the direction of the force (m)
What is the symbol equation for work done
E = F x d
What is power?
The rate at which energy is transferred.
What is power measured in?
watts (W)
What does 1 watt equal in terms of work done?
1 joule per second
If there are 2 same sized boxes lifted, what makes the person produce a different power?
If it is lifted in a shorter time
What is the word equation for power?
Power (W) = work done (J) / time taken (s)
What is the symbol equation for power
P. E / t
What are contact forces?
When objects are touching and they exert a force on each other
Give an example of a normal contact force?
When you stand on the floor and there is an upward force from the floor on you
Give an example of a non-contact force
Upthrust and gravity on a boat
Why does the moon stay in orbit around the earth?
The two bodies are attracting to eachother
What are action-reaction forces.
Pairs of forces acting on different objects in opposite directions
What is a force field?
The space around an object where it can affect other objects
Why do the moon and the earth affect eachother?
They are within each others gravitational field
What is magnetism and static electricity
Other forces that affect objects that are not in direct contact
What is a magnet?
An object that attracts objects made from magnetic materials
What materials are magnetic? (3)
Nickel, iron, cobalt
What is a magnetic field?
The space around a magnet where it can affect other materials.
What is an electric field (electrostatic field)
The area around a charged object where it can affect its surroundings.
What is the net force?
The resultant force, the overall force, if it isn’t balanced, there is a net force but if the are balanced, the net force is 0
What is a free body force diagram?
A diagram using arrows to show forces and a simple box to show the object
What does a scale diagram help to show
Hoe different forces act when they are not in opposite directions
How doe you draw a scale diagram for finding the resultant force?
Create scale (in N or kN)
Draw a line to scale and use angle to draw second line
Total angle is 360 in parallelogram so use this to work out other angle.
Calculate force by measuring diagonal from the object corner.
How can a scale diagram be used to calculate forces acting on an object?
Create scale (in N or kN)
Draw base line and second line using angle and force given.
Draw rectangle from this (use base line) and work out force using scale.
What is a moment
A turning force
What does the size of the moment depend on?
The size of the force and where it is applied
What makes a bigger moment?
A greater force and further from the pivot
What is the distance between the force and pivot measured from?
It is measured normal to the direction of the force
What is the word equation for a moment?
Moment (No) = force (N) x distance normal (m)
What does it mean for 2 objects to be in equilibrium in terms of moments
The anti-clockwise force is equal to the clockwise force.
What is effort?
The amount of force that something exerts
What is the force that acts upwards of someone standing
Upwards push or normal force
