Topic 8 Flashcards
Work done =
Force x distance moved in diraveyuon of force
J. N. M
Power =
Works done / time taken
J. S
The energy of a system can be changed by
Work done through forces
- a body can be lifted through a vertical height by a force. This will increase the store of GPE
Electrical equipment
- a cell in a circuit provides a potential difference so that components in the circuit can transfer energy into other forms such as thermal
Heating a material
- supplying thermal energy to a system will increase the Ke of the particles in the material. It’s temperature will increase if it is not changing state.
Pairs of forces can interact at
A distance or by direct contact
Forces can be exerted between objects without them being in comtact with one another. There are three non-contact forces you need to know about
Gravity
Magnetism
Electrostatic charges
Gravity
Acts between allxnasses. It’s always attractive
Magnetism
Acts between magnetic poles unlike poles attract and like poles repel
Electrostatic charges
Exert forces on each other at a distance unlike charges attract and like charges repel
Forces can be exerted between objects due to them being
In contact
The normal contact force acts
Upwards in opposition to the weight of the object
The interaction pair is the force of the ground on the box and the force of the box on the ground
An archer fires an arrow from a bow. Describe the contact and non-contact forces involved in firing the arrow
Contact forces include the normal force acting on the arrow
Friction as it moves through the air and the tension in the string
Non contact forces include gravity once it has been released
A resultant force can be resolved into its
Horizontal and vertical component forces
What do free body diagrams show
The forces acting on a single object
Free body diagrams contain
The body the forces are acting on - this can be simplified to a box or a dot
The forces acting on the body
- this will depend on the complexity of the problem and the assumptions being made
Resultant forces determine wether a body will be
Stationary
Moving at constant speed
Accelerating
What is a moment
When Forces act at a distance from a pivot cause a turning effect or roatation
Moment =
Force x distance normal to the direction of the force
Nm. N. M
The distance must be measure from the pivot normal to the direction of the force. The pivot is the
Point about which the object rotates
What is the principle of moments
Sum of clockwise moments = sum of anti-clockwise moments
For riatational forced in an equilibrium
A lever can cause a rotation which depends on the position of
The input force
The output force
The fulcrum
Gears are
Toothed wheels that are meshed together to transmit rotational force and motion.
Each gear in a series reversed the direction of motion
A larger fear will roatate more slowly than a smaller gear but will have a greater training eggevt
A low gear leads to a low speed and a high turning effect
A Hugh gear is when
A large input gear turns s smaller output gear
High speed
Low turning effect
A low gear
is when s smaller input gear turns s larger gear
Low speed
Hugh turning effect
Describe he common features of gears and levers in terms of how they work
Gear and levers both transmit the rotational effect of a force and they can alter the size of the output force compared with the input force
Look at component symbols
Make actual Flashcards
Series circuits
Contains just one loop which an electric current can flown
Characteristics of series circuits
Electrons do not flow through any of voltmeters
Ammeters are always connected in series with components
The size of the current in a series circuit is the same at every point in the circuit. All three ammeters in this circuit will show the same value for current
Voltmeters have a very high resistance so that no current will flow through them
The pd accord components that are arranged in series must add up to give the cell voltage
Parallel circuits
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