1) Motion Forces and Energy Flashcards
scalar quantity
A scalar quantity is a quantity that has magnitude (size) only. Examples of scalars: distance, speed, time, mass, energy and temperature
vector quantity
A vector quantity is a quantity has magnitude and direction. Examples of vectors: force, weight, velocity, acceleration, momentum, electric field strength and gravitational field strength
speed
Speed is the distance travelled per unit time
acceleration
Acceleration is the change in velocity per unit time
velocity
Velocity is the speed in a given direction
Average speed
Average speed is defined as total distance / Total time
Free-fall
An object is in free-fall when it is moving only under the influence of the earth’s gravity.
Acceleration of free fall
It is a value of the acceleration of free fall (g). On Earth, this value of g for any object that is near the surface is approximately constant at 9.8m/s2
Mass
Mass is a measure of the quantity of matter in an object at rest relative to the observer
Weight
Weight is defined as a gravitational force on an object that has mass
gravitational field strength
ravitational field strength is the force per unit mass
Spring constant
Spring constant is defined as the force per unit extension. Its formula is: k=F/x
density:
Density is defined as the mass per unit volume
Limit of proportionality:
It is a point beyond which the spring crosses its elastic limit and becomes permanently deformed.
Newtons second law:
It states that, for a body of constant mass “m” and net force “F”, we can state that F = ma, where F ( net force) and a (acceleration)/ Both are vector quantities.
Circular motion
Circular motion is defined as the movement of an object along the circumference of a circle or the rotation of an object along a circular path.
Solid friction
Solid friction as the force between two surfaces that may impede motion and produce heating.
Drag force
It is a force acting in a direction that is opposite to the relative motion of the object moving with respect to the surrounding fluid. Fluid refers to liquids and gases
Moment of a force
It is a measure of the turning effect of a force. Formula is moment = force × perpendicular distance from the pivot. The SI unit of moment of a force is Nm
Principle of moments
For an object in equilibrium, the sum of the clockwise moments about a point is equal to the sum of the anticlockwise moments about the same point and the net force acting on it is zero
Centre of gravity
It is a point at which the weight of a body or system is supposed to be concentrated. In uniform gravity it is the same as the centre of mass.
Momentum
Momentum=mass × velocity; recall and use the equation p = mv. The SI unit of momentum is kgm/s
Impulse
orce × change in time. [ it is the time for which force acts]. The Si unit of impulse is Newton-second (Ns)
State the Principle of conservation of momentum
When 2 or more bodies interact (collide) in an isolated system, the total momentum stays the same.
Define Resultant force
A resultant force is the change in momentum per unit time. The unit is Newtons (N)
Define Kinetic energy
The energy possessed by an object, by virtue of its motion is called as kinetic energy.
Define Gravitational potential energy
mgh
Define Chemical energy
The energy stored in the bonds of chemical compounds is called as the chemical energy.
Define Elastic (Strain energy):
Strain energy is the energy stored in an object due to its deformation.
Define Electrostatic energy
It refers to the potential energy of a system of separated electric charges
Define Internal (Thermal) energy
The energy of a thermodynamic system is its internal energy. It is the energy associated with the random, disordered motion of molecules
State the Principle of conservation of energy
Principle of conservation of energy states that “ Energy can never be created nor destroyed. It can only be converted from one form to another. The total amount of energy in a system stays the same.
Define Work
Work is= Force x displacement. Here the displacement is in the direction of the force. Unit of work is Joule.
Define One Joule
One Joule refers to the work done by a force of 1 Newton, when it displaces a body through 1m in the direction of the force applied.
Define Solar cells [ Photovoltaic cells]:
This refers to cells that are capable of converting light energy to electrical energy through photovoltaic effect
Define Wind energy:
The energy of the naturally flowing air that is used to generate electricity is called as wind energy.
Define Renewable energy resources:
This is the type of energy that comes from resources that are easily replenished. Example: Energy from the sun, wind, etc.
Define Non-renewable energy:
This is the type of energy that comes from resources that are easily not easily replenished. Example: Energy from fossil fuels
Define Percentage Efficiency:
Percentage efficiency= {[ Useful energy output] /Total energy input]} x 100 or { [ Useful power output] /Total power input]} x 100
Define Power
Power is defined as the work done per unit time of power is defined as the energy transferred per unit time.SI unit power is Watts (W)
Define Pressure:
Pressure is defined as the force per unit area.SI unit of pressure if Pascals (Pa). Formula for calculating pressure due to solids=Force/Area; While the formula to calculate the pressure exerted due to liquids is=hpg. Where h is the height of the liquid column, p is the density of the liquid and g is the gravitational field strength.
Kinetic
Moving objects have energy in their kinetic store
Gravitational
Objects gain energy in their gravitaional potential store when they are lifted through a gravitational field
Elastic
Objects have energy in their elastic potential store if they are streched, squashed or bent.
Magnetic
Magnetic materials interacting with each other have energy in their magnetic store.
Electrostatic
Objects with charge (like electrons and protons) interacting with one another have energy in their electrostatic store.
Chemical
Chemical reactions transfer energy into or away from a substances chemical store.
Nuclear
Atomic nuclei relases energy from their nuclear store during nuclear reactions
thermal
All objects have energy in their thermal stores; the hotter the object the more energy it has in their store.
Mechanical Working
When a force acts on an object
Electrical working
A charge moving through a potential difference (eg: Current)
Heating (by particles)
Energy is transferred from a hotter object to a colder one (Eg: conductions)
Heating (by radiation)
Energy transferred by the EMS waves (eg: visible light)
Advantages and DIsadvantages of Solar energy
A:
- No pollution
- Free Energy source
D:
- Doesnt work at night
- Doesnt work well in winter
Advantages and DIsadvantages of Wind Energy
A:
- No pollution
- Free Energy Source
D:
- Nosiy
- Can kill birds
- Needs large land space
Advantages and DIsadvantages ًWave Energy
A:
- No pollution
- Free enrgy source
D:
- Difficult installation
- May affect shipping
Advantages and DIsadvantages Tidal Energy
A;
- No pollution
- Free Energy source
D:
- Difficult maintenance
- May affect shipping
- Expensive
Advantages and DIsadvantages Hydroelectric Energy
A;
- No pollution
- Free Energy source
D;
- May flood behind the dams
- May effect boat routes
Advantages and DIsadvantages Bio mass energy
A:
- USe waste products
- Abundant
D:
- Can produce methane greenhouse gases
- Can be smelly
Advantages and DIsadvantages Geo thermal Energy
A:
- Little pollution
- Free energy source
D:
- nly available in some parts of the world
- The heat used up after few years.
Advantages and DIsadvantages Nuclear Energy
A:
- Can produce electricty
- Does pollute the atmosphere
D:
- Generate radioactive waste materials with very long half life
- Places for safe dumping or storing
- Expensive
Advantages and DIsadvantages Fossil FUels
A:
- Oil useful in petrol
- A raw material for most plastics
D:
- Limited supplies
- Waste gases pollute the atmosphere.
Non Renewable Energy
Sources that will run out
Renewable Energy
Sources that will never run out
Newtons Third LAw
Every action has an oppositie reaction
Terminal velocity
Acceleration due to weight speed and drag increases acceleration decreases when drag = weight there is no resultant force and then speed decreases
