Energy, Forces, and Motion Lecture Notes

Flashcards from lecture notes on energy, forces, and motion.

Power

The rate of energy transfer or the rate at which work is done.

Watt (W)

The unit for power, equivalent to one joule transferred in one second (1 J/s).

Efficiency

The measure of how much of the stored energy in a system is transferred usefully.

Appliance

A device that transfers electrical energy to other forms.

Elastic

Objects that return to their original shape after being deformed by a force, once the force is removed.

Elastic Deformation

Deformation where the object returns to its original shape once the force is removed.

Deformation

Bending, stretching, or compressing an object.

Extension

The change in length of an object, such as a spring, when a force is applied.

Directly Proportional

A relationship where for every increase of one variable by one unit, the other increases by the same amount.

Limit of Proportionality

The limit of a directly proportional relationship, after which the relationship becomes non-linear.

Gradient

Calculated by dividing the change in the variable on the y-axis by the change in the variable on the x-axis.

Weight

A force caused by gravity acting on mass, measured in newtons.

Mass

Measures the amount of material in an object, measured in kilograms (kg).

Gravitational Field Strength

The measure of how strong the gravitational field of a large object is, measured in N/kg.

Centre of Mass

The point at which the weight of an object is considered to act – the ‘middle’ of the object's mass.

Newton Meter

A device to measure weight consisting of a spring and a calibrated scale.

Energy Store

A system or object that can store energy, such as objects up high, fuels, and stretched springs.

Energy Transfer

The change of energy from one store to another, also known as work.

Dissipate

Means ‘spread out,’ referring to energy being stored in less useful ways during energy transfers.

Thermal Insulation

Insulation that reduces the transfer of thermal energy to the surroundings.

Energy Resources

Stores of energy on Earth that can be accessed and transferred to useful forms, such as electricity.

Nuclear Fuel

Elements, like uranium, that can be used to release massive amounts of energy for generating electricity.

Fossil Fuel

A fuel made from hydrocarbons that formed millions of years ago from the bodies of animals and plants; a store of chemical potential energy.

Geothermal

The energy resource found in Earth’s crust, due to the thermal energy of the rock.

Biofuel

Any type of fuel made from living organisms – such as fuels made from plants.

Hydroelectricity

Water stored behind a dam that has gravitational potential energy.

Tidal Energy

The kinetic energy of the massive movement of water in tides that can be transferred usefully to electrical energy.

Wave Energy

The kinetic energy of ocean waves that can be transferred usefully to electrical energy.

Solar Energy

Using solar panels, we can transfer wave energy directly into electrical energy.

Renewable

Describes energy resources that are, or can be, replenished (replaced) as they are used.

Non-renewable

Describes energy resources that cannot be replenished and get used up.

Scalar Quantity

Quantities that have only a magnitude.

Vector Quantity

Quantities that have both magnitude and direction.

Contact Force

Forces that act when interacting objects are physically touching.

Non-contact Force

Forces that act when interacting objects don’t have to be touching.

Quantity

Anything that can be given a numerical value.

Magnitude

The size of a quantity.

Force

Pushes or pulls that act on an object, resulting from objects interacting with each other.

Resultant Force

The overall force acting on an object when multiple forces are applied.

Displacement

Represents the difference between an object's initial and final position; a vector quantity.

Joule (J)

The amount of energy transferred by doing work; 1 joule is 1 newton metre.

Speed

The rate at which an object's position changes, measured in meters per second.

Velocity

The speed of an object in a particular direction.

Acceleration

The measure of how quickly velocity changes.

Deceleration

A negative acceleration (slowing down).

Stopping Distance

The distance a vehicle travels after the driver spots a danger and decides to stop.

Thinking Distance

Distance travelled during a driver’s reaction time.

Braking Distance

Distance travelled while the driver is applying the brake.

Kinetic Energy

The form of energy of any moving object; a scalar quantity.

Thermal energy

The form of energy associated with heat.

System

An object or group of objects, and its/their interactions.

Conservation of energy

A fundamental concept in physics; total energy is always conserved (it cannot be created or destroyed).

what’s the charge of protons

+1

what’s the charge of neutrons

0

what’s the charge of electrons

-1

how do we work out neutrons

minus atomic mass by atomic number