Global Systems S2

What are some examples of contact forces

• frictional force

• tension force

• normal force

• air resistance

• applied force

• spring force

What are some examples of non-contact forces

• gravitational force

• electromagnetic force

• nuclear force

Define a force and what an application of a force can change

A force is a push or pull on an object.

The application of a force can:

1. change an object’s speed

2. change an object’s direction

3. change an object’s shape

Define a contact force and provide 3 examples

A contact force is applied directly to the body through physical contact. When the contact ceases, the force also ceases

e.g. hitting a ball, collisions, frictional forces

Define a non-contact force and provide 3 examples

The force is applied without direct contact. In such case, the force may never cease to act upon the body

e.g. gravity, magnetism, electrical forces

What are 2 forces that act upon a car when it’s in motion?

1. Thrust - same direction of the motion of the car (forwards)

2. Drag - opposite direction (backwards)

What is the net force?

The net force is the combined effect of all the forces acting on an object.

• if forces are in the same direction, the magnitude is added

• if forces are in the different, the magnitude are subtracted

Define a balanced force

A balanced force is when the net force is 0 Newtons. An object will remain motionless or travel at a constant velocity when forced are balanced.

Name the 4 spheres of the Earth

1. Atmosphere - the air

2. Hydrosphere - the waters

3. Lithosphere - the Earth’s crust and mantle

4. Biota - all living things

   These make up the biosphere

How does the greenhouse effect work

1. shortwave radiation (from sun) passes through Earth’s atmosphere

2. Reflects off Earth’s surface as longwave radiation

3. Longwave radiation is absorbed and re-radiated by greenhouse gases

What are factors that affect climate

1. Surfaces of the earth - the sun provides radiant heat and not all surfaces absorb the same amount snow: 84% forest: 16% water: 6%

2. The Earth’s orientation - earth’s axis is on a tilt so hemispheres experience different intensities of the sun’s radiation as the Earth revolves

3. Ocean and wind currents - warm air goes to cool regions and cool air travels to warm regions

Explain the difference between weather and climate

Weather is the state of the atmosphere in terms of temperature, wind, cloud cover and precipitation at any give time.

Climate is long-term averages of weather conditions

What is the enhanced greenhouse effect

Human activity has led to significantly more gases being released into the atmosphere. This causes a higher retention of heat energy. This is believed to be contributing to global warming

Define stars and how they get their structure

Stars are massive, dense, luminous spheres of plasma held together by gravitational force. Star structure is determined by the balance between two opposing forces:

• the inwards force of gravity into the centre of the star

• the outwards force of radiation pressure caused by heat radiated from the sun’s core n

What are nebulae?

Nebulae are giant clouds of dust and gas that may collapse and heat up due to gravity forming stars and planets

How are nebulae formed?

They are formed by the most violent explosion - supernovas (the death of stars)

What are galaxies

Galaxies are enormous collections of stars, planets, gases and dust bound by gravity

What are 3 types of galaxies?

1. spiral - flattened disk with a central bulge

2. elliptical - spheroid/elongated sphere shape

3. irregular - no symmetrical shape or structure

How does light travel?

Light travels at a constant speed through a vacuum (299, 792, 458 m/s). Light travels (9.5 × 1-