Application of forces and transfer of energy

Sec 2 science

Frictional force

The force that opposes motion between two surfaces

Elastic force

The force acting on a stretched or compressed elastic object to return it to its original shape.

Magnetic force

The force exerted between a magnet and another magnetic material (eg cobalt, iron, nickel, steel)

Gravitational force

Force that attracts two object towards each other

What is weight?

The gravitational force that a planet exerts on an object

What is mass?

Amount of matter in an object

What can mass be measured by?

Electronic balance, beam balance

What can weight be measured by?

Spring balance

What is the relationship between mass and weight?

Weight = mass x grams

The transfer of energy between objects can?

Move a stationery object, change the speed of an object, change the direction in which an object moves, stop a moving object, cause changes in the size and/or shape of an object, cause pressure to be exerted

What is the formula of pressure?

Force/area

What is the unit of pressure?

Pascal (Pa) or N/m squared

When is work done?

When a force moves an object through a distance in the direction of the force

What is the unit of work done?

joule (J)

What is the formula of work done?

Force x distance

Gravitational potential energy

Energy that is stored in an object due to its position or height above the ground

Kinetic energy

The energy that an object possesses due to its motion

Elastic potential energy

Energy stored by stretching or compressing an elastic object

Chemical potential energy

Energy stored in chemical bonds of a substance. The energy can be released through chemical reactions

Law of conservation of energy

Energy cannot be destroyed, it can only be converted from one form to another or transferred from one body to another. The total energy of an isolated system remains constant.

Nuclear energy

Energy released during a nuclear reaction

Thermal/ internal energy

Energy possessed by a body that has heat

Solar energy

light energy —> electrical energy

Solar energy’s impact on environment

Disposal of solar panels can generate toxic waste

Hydroelectric energy

Gravitational potential energy —> kinetic energy —> electrical energy

Hydroelectric energy’s impact on environment

-Area behind the dam would be flooded, killing plants

-The dams prevent the flow of sediments and nutrients down rivers, affecting ecosystems

Wind energy

Kinetic energy —> electrical energy

Wind energy’s impact on environment

-Large plots of land need to be cleared to build wind farms, destroying the habitats of wildlife

-Birds can collide into the rotating blades of turbines and get killed

Geothermal energy

Heat energy —> kinetic energy —> electrical energy

Geothermal energy’s impact on environment

-Large areas of land need to be cleared, destroying the habitats of wildlife

-Toxic elements buried underground are drawn out and can harm the environment

Biofuel energy

Chemical potential energy —> heat energy —> kinetic energy

Biofuel energy’s impact on environment

The burning of biofuels releases air pollutants such as carbon dioxide to the environment

Nuclear energy

Nuclear energy —> heat energy —> kinetic energy —> electrical energy

Nuclear energy’s impact on environment

There are potential risks to health and safety of communities living near nuclear power plants