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Learning outcomes for this UNIT:
Learning outcomes for this UNIT:
By the end of the topic, learners will be able to:
• Explain that a force is a push or pull (or twist) exerted on an object
• Identify Newton as the unit of measure for force
• Explain that a force can change the shape, direction, and speed of an object
• Explain that all forces acting on an object can be placed in two groups - contact forces and non-contact forces
• Explain that forces act in pairs.
• Describe contact forces and field forces
• Give examples of contact forces and field forces
• Give one difference between contact forces and field forces
• Differentiate between a tension force and a compression force
• Explain that a field force results from action-at-a-distance between two bodies.
• Explain that a field force results from action-at-a-distance between two bodies
• Describe the force of gravity
• Explain that objects with greater mass have more gravitational pull on each other
• Explain that force decreases as the distance between the objects increases
• State the unit of measurement of gravity
• State four differences between weight and mass.
• Explain that a magnetic force is a force that two magnetic materials exert on each other a distance
• Explain that magnets attract magnetic substances
• Define a magnetic field
• State that all magnets have a magnetic field and two ends/ poles.
• Explain that when certain materials are rubbed together they can acquire an electrostatic charge
• Explain electrostatic charge in terms of the movement of electrons
• Describe forces between unlike and like charges.
• Explain that charged objects in an electrostatic system possess potential energy
• Describe the cause of a lightning strike
• List safety precautions that should be taken during thunder and lightning storms.
Types of forces
Types of forces
(a) A force can be defined as a push, pull, or twist acting on an object.
(b) The unit used to measure force is Newton (N) named after Sir Isaac Newton.
(c) Forces always act in pairs, e.g. when a force pushes an object forward another is acting in the opposite direction.
(d) A force can change the direction of an object, speed, shape, or stop an object in motion.
Examples of effects of a force
Pushing a trolley: the applied force causes it to accelerate.
Opening a door: the applied force at the edge of the door causes it to rotate around its hinges.
Squeezing a loaf of bread: The force applied changes the shape and size of the bread.
A goalkeeper stopping a ball: A force is applied to stop the movement of the ball.
With the use of ChatGPT or any other OpenAI platform. Complete this activity in your books and upload a picture on Google Classroom. A link will be opened named Classwork 1 forces.
Name the following forces:
1. A force that tries to slow things down when two things rub together.
2. A force from water that brings water to your house.
3. A force that acts in the opposite direction of things that are moving through the air.
4. The force that enables the Earth to pull things towards itself.
5. The objects that attract and repel each other and also attract things made of iron.
CONTACT FORCES
(a) Contact force (including friction, tension, and compression) is a result of contact/touching between bodies.
(b) The contact can also be through a medium such as a rope, cable, bar etc.
NON-CONTACT FORCES (FIELD FORCES)
Field forces are forces that can act at a distance from each other or can create a field around them such as gravity, magnets, and electrostatic forces.
Complete the activity below in your books and upload a picture on Google Classroom. A link will be opened named Classwork 2 forces.
MAGNETIC FORCE
(a) Magnets attract magnetic materials such as iron, steel, cobalt and nickel.
(b) A magnet has a north and a south pole with like poles repelling and unlike poles attracting.
(c) Just like a magnet, the Earth has a magnetic field with its South Pole under
Earth's magnetic North pole.
Complete the activity below in your books and upload a picture on Google Classroom. A link will be opened named Classwork 3 forces.
Looking at the diagram below:
What are the two poles in a magnet?
What is observed when the same poles of a magnet are brought against each other?
Looking at the magnets, what do you observe about the iron filings?
What do you think the iron filings are made of?
Magnets are examples of non-contact forces because they (create /don’t create) magnetic fields around them.
Explain by referring to your answer in 3 why non-contact forces are also called field forces.
GRAVITY
(a) There is a pulling force between objects which varies according to their masses. Such a pulling force is observed between objects on Earth and the Earth, the Moon and the Earth, the Earth and the Sun, and the Sun and the planets moving around it.
(b) According to a scientist known as Sir Isaac Newton, the pulling force between objects is directly proportional to the masses of the objects.
(c) The force is also affected by the distance between the forces, the force is inversely related to the distance between them.
Complete the activity below in your books and upload a picture on Google Classroom. A link will be opened named Classwork 4 forces.
ELECTROSTATIC FORCE
(a) Rubbing materials together results in a gain or loss of electrons.
(b) The loss of electrons leaves the material positive and a gain of electrons results in the material being negatively charged.
(c) Like charges repel while unlike charges attract each other.
Complete the activity below in your books and upload a picture on Google Classroom. A link will be opened named Classwork 5 forces.
1. How does a material become positively charged?
2. How does a material become negatively charged?
3. Discuss what happens in C.
4. Try the experiment in B and then explain how the balloon was able to attract the water.
5. The Van de Graaff generator becomes charged as the belt is scratched and loses electrons and it then transfers the charge to the dome. Explain why the dome is positively charged.
6. How does the metal sphere discharge the dome?
7. Explain what is happening in D.
8. Lightning is a natural form of static electricity. When lightning strikes, it is a result of the discharge or release of a charge between the clouds carrying a charge and the ground. Research utilizing ChatGPT and other OpenAI platforms safety precautions that must be considered during thunder and lightning storms.
ADDITIONAL RESOURCES:
ADDITIONAL RESOURCES:
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