Multiple forces
This Topic is About...
- I will learn to identify different forces like gravity, friction, upthrust, air resistance, and water resistance.
- I will see that an object can have more than one force acting on it, even when it is not moving.
- I will make and test a paper aeroplane to show how forces act when it is at rest and when it is flying.
- I will use force diagrams to show the names and directions of forces.
- I will make predictions and test them using my knowledge of forces.
- I will describe how accurate my predictions are, based on results.
- I will suggest ways to improve my paper aeroplane and explain my ideas.
- I will make a conclusion from my results using my knowledge of forces.
You’re going to be a forces explorer!
Key Words
- multiple
- thrust
Tap to Learn the Meanings!
- multiple: More than one or many of something.
- thrust: The forward push that moves an object, like a plane or rocket, through air.
Excellent! You now know two key science words about forces and motion.
Many Forces Act Together ⚙️
All objects are affected by several different forces or multiple forces at once. The strongest force causes the change of an object. The change might be a change of shape, a change of position, or a change in the speed an object is travelling.
Forces on a Rolling Ball 🏀
Look at this example of Sofia rolling a ball. There are several forces acting on the ball:
- Applied force, as Sofia pushes the ball.
- Gravity pulls the ball down towards the Earth.
- Air resistance slows the ball down once it is moving.
- Friction with the floor slows the ball down once it is moving.
Forces When Riding a Bicycle 🚴♂️
Gravity pulls Marcus and his bicycle towards the centre of the Earth. Friction between the tyres and the road pulls him back, and air resistance also pushes against him.
To overcome the air resistance and friction, Marcus must push on the pedals to move forwards. This forward push is called thrust. Thrust is an applied force.
Designing Better Bicycles 🛠️
Professional cyclists use carefully designed bicycles made with strong but lightweight materials. Designers use science to make tyres and gears suitable for different surfaces like rough or smooth roads and mountain paths.
Forces Acting on Aeroplanes ✈️
Air resistance and gravity are the two forces that act on anything lifted from the Earth and moved through the air. To overcome these forces, we have to create our own forces of thrust and lift. An aeroplane is a good example of these forces. It uses its wings and engines to lift off the ground and move forward through the air. You can try this in the next activity!
🔍 Think Like a Scientist: Make and Test a Paper Aeroplane
🧰 You will need: A sheet of A4 paper
📝 How to Make Your Paper Aeroplane:
- Fold the paper in half vertically.
- Unfold the paper and fold each of the top corners into the centre line.
- Fold the top edges into the centre line.
- Fold the plane in half toward you.
- Fold the wings down, matching the top edges with the bottom edge of the body.
- Hold your aeroplane under the wings and launch it into the air! ✈️
🌟 Try this next!
Experiment with your aeroplane’s design — try different wing shapes or folds and see how they change the distance and flight path! 🚀
🔍 Let’s Investigate: Test Your Paper Aeroplane!
🧪 What to Do:
- Stand on a chair and raise your arm to drop your small paper aeroplane. ✈️
- Use a stopwatch to time how long it takes for the aeroplane to reach the ground. ⏱️
- Repeat three times to check your results. 🔁
- Decide if you need to repeat more times to get better data. 📊
- Record all your results in a table. 🧾
- Predict whether a larger aeroplane will fall faster or slower than the small one. 🤔
- Repeat all steps using the larger aeroplane to test your prediction. 🛩️
- Which forces act on your aeroplane when it is at rest?
- What do you think will happen when you throw it up into the air?
- When you threw it upwards, which two natural forces acted on it?
- What applied forces did you create to overcome those forces?
- Name the four forces on the diagram of your paper aeroplane. 🪁
- What happened when you threw it? Was it what you predicted?
- Why did the aeroplane eventually fall to the ground?
- What changes could make your aeroplane stay in the air longer?
- How do real pilots prevent aeroplanes from falling to the ground?
- Write a conclusion about how aeroplanes overcome forces and fly. 🌤️
- Can I identify forces on a force diagram of a paper aeroplane? 🧠
- Can I draw a force diagram much easier than before? ✏️
- Do I still need more practice? 💪