Science-global studies

Define a force

A force is a push, a pull or a twist. We measure forces in Newtons (N)

compare contact and non-contact forces

Similarities: both are forces that can cause objects to change shape, change speed, or change direction. 

Differences: contact forces must act when objects are touching, for example friction and tension. 

Non-contact forces can act at a distance, for example gravity and magnetism. 

Distinguish between balanced and unbalanced forces 

When forces are applied to an object, if there is no net force, they are balanced. When forces are not balanced, they cause a change in shape, speed or direction. 

Identify the forces acting on an object in straight-line motion on a horizontal surface 

Object is pulled down by gravity (F_g). The surface resists gravity, pushing upwards with an equal and opposite force called the reaction (F_R). Other forces include any applied forces (F_A) and friction (F_F) acting in the opposite direction to the motion. Length of arrow represents size of force. 

To be able to distinguish between quantities of distance and displacement. 

Distance is a scalar quantity, so has magnitude only. For example 100m is a distance. Displacement is a vector quantity, so has magnitude and direction. For example 100m East is a displacement. 

To be able to calculate and distinguish between quantities of speed, velocity and acceleration.  

Speed is distance divided by time, so is scalar as it has not direction. For example, 30 m/s. Velocity is displacement divided by time, so is a vector and has direction. For example, 60 km/h North  >Acceleration is velocity divided by time (change in velocity). For example, 10 m/s². Acceleration is velocity divided by time (change in velocity). For example, 10 m/s² 

Recall Newton’s 1^st Law of Motion 

Newton's 1st Law: 

An object at rest will remain at rest, and an object in motion will continue in motion with the same speed and in the same direction unless acted upon by an unbalanced external force.

Explain how Newton’s First Law of Motion relates to car safety 

Newton’s First Law of Motion says that things want to keep doing what they’re already doing-they stay still if they’re still, or keep moving if they’re moving, unless something makes them stop or change direction. 

 

How this relates to car safety: 

 

• When a car is moving, you and everything inside are moving at the same speed as the car. 

 

• If the car suddenly stops (like in a crash), your body wants to keep moving forward at the same speed, even though the car has stopped. 

 

• If you’re not wearing a seatbelt, you could keep moving forward and hit the dashboard, windscreen, or seat in front of you, which can cause serious injuries. 

 

• Seatbelts and airbags are car safety features that act as the “outside force” to stop you safely. They hold you in place or cushion you, so you don’t keep moving forward and get hurt. 

 

Recall and describe the four spheres of Earth 

the four spheres of Earth are interconnected systems that make up our planet. Each represents a major component of Earth's environment: 

 

1. Atmosphere – The layer of gases surrounding Earth. 

 

2. Hydrosphere – All the water on Earth. 

 

3. Geosphere (or Lithosphere) – The solid part of Earth. 

 

4. Biosphere – All living organisms on Earth. 

 

These spheres constantly interact—for example, a volcanic eruption (geosphere) can release gases (atmosphere), affect nearby rivers (hydrosphere), and impact plant and animal life (biosphere). 

Differentiate between weather and climate 

Weather is the atmospheric conditions at a point in time, such as the temperature, rain and wind conditions. Climate is the average of weather conditions over a long period of time. 

Identify the factors that influence climate. 

The main factors that influence climate are: 

• The surfaces of the Earth 

• The orientation of the Earth 

• The gases in the atmosphere

Describe ocean and wind currents and recall the phenomena that cause them  

Ocean and wind currents are driven by warmer water or air moving towards cooler regions. As fluids warm up, the particles move apart so the fluid becomes less dense. It is this difference in densities that drives the circular motions known as currents.

Define a greenhouse gas

Define a greenhouse gas 

A greenhouse gas is defined as a gas that can trap heat in the atmosphere, warming the Earth's surface. 

Examples include carbon dioxide, water vapour, methane, nitrous oxide and ozone. 

Explain the causes of the greenhouse effect 

Heat from the sun enters the atmosphere. Some is absorbed, but a lot of heat is reflected off the Earth's surface. If there are greenhouse gases in the atmosphere, the heat reflects off them, back towards the Earth's surface. This helps keep the Earth warmer. Without greenhouse gases the Earth's surface would be frozen. 

Identify the major contributing factors towards the enhanced greenhouse effect

• Burning fossil fuels – like coal, oil, and gas for cars, factories, and electricity. 

• Cutting down trees – forests help absorb carbon dioxide, so losing them makes it worse. 

• Farming – especially cows, which release methane gas. 

• Factories – some release greenhouse gases into the air. 

• Waste – rotting rubbish in landfills gives off methane. 

Predict the consequences on global systems and biodiversity if the enhanced greenhouse effect continues 

If the enhanced greenhouse effect continues: 

• Weather will become more extreme, with stronger storms, floods, and droughts. 

• Ice at the poles will melt, making sea levels rise and flooding coasts. 

• Oceans will get warmer and more acidic, harming sea life like coral. 

• Animals and plants may lose their homes and struggle to survive. 

• Ecosystems could break down, leading to less biodiversity (fewer types of living things).

Define a light-year 

A light year is defined as the distance that light travels in a year. 

We use light years to measure the large distances in space. 

A light year is 9,460,730,472,580,800 metres! 

Define galaxies, stars, nebulae, and black holes 

Galaxies – Huge collections of stars, gas, dust, and dark matter all held together by gravity. Our galaxy is called the Milky Way. 

Stars – Big balls of hot, glowing gas (mostly hydrogen and helium) that give off light and heat. The Sun is a star. 

Nebulae – Clouds of gas and dust in space. Some nebulae are where new stars are born, while others are leftovers from dead stars. 

Black Holes – Regions in space where gravity is so strong that nothing, not even light, can escape. They often form when very massive stars collapse. 

Explain the reasons why the big-bang theory has superseded the steady-state theory  

The steady-state theory says the Universe is unchanging. 

The big-bang theory says the Universe had a beginning - a huge explosion called the "big bang" and it is growing and changing. 

There is lots of evidence that the Universe is changing including: 

• Redshift of galaxies - shows galaxies are moving away from Earth. 

• Cosmic microwave background radiation - left over from the big bang. 

• More distant galaxies look different to closer ones, showing they are changing over time. 

use the raisin-loaf model to describe the expanding universe 

Imagine a loaf of raisin bread dough rising in the oven. 

• The dough is like space. 

• The raisins are like galaxies. 

As the dough rises (expands), the raisins move farther apart from each other—even though they’re not moving on their own. The dough between them is stretching. 

That’s just like the universe! Space itself is expanding, so galaxies move away from each other, just like the raisins in the growing loaf.