LESSSON TITLE: FORCES: NEWTON’S FIRST LAW OF MOTION, BALANCED

&UNBALANCED FORCES

SUBJECT: PHYSICS (INTRODUCTORY)TARGET GROUP: HIGH SCHOOL (15YRS.)

Science Power (SP)Electronic learning environments & E-learning

design

Aims & Objectives

To encourage self-regulated learning

To ensure 24/7 online accessibility for

learners

To give timely feedback and information

Platform for storage of prior lessons

Target group

High school students

Science students

14yrs – 16yrs

Learning objectives

Students remember previous knowledge (scafolding)

At the end of the lesson students will be able to differenciate types of forces

Students will understand the concept of force

Know and be able to apply the Newton’s first law of motion

Be able to give examples of balanced and unbalanced forces

Pre-assessment

1) A stationary object has no forces acting on it. True or False

2) A stationary object has net or balanced forces acting on it. True or False

Feedback When you push on a stationary object, you are applying a force. Despite

this, you still might not be able to accelerate it. That is because there might be another force that nets against yours.

For example, you push on a beached whale. The reason why you can't accelerate it is because the force of friction between the whale and the sand perfectly nets against (same magnitude, opposite direction) the force you are applying.

For another example, you're presumably not plummeting to the center of the Earth right now despite the fact that Earth's gravity is pulling on you. This is because your chair is exerting a normal force in the opposite direction (radially outwards from the center of Earth) that perfectly offsets the force of gravity.

This statement would have been true for question one, if it said “balance forces", not just "forces".

Scaffold

Last lesson, we defined force as any interaction which tends to change the motion of an object

Forces are also described as a push or pull on an object. They can be due to phenomena such as gravity, magnetism, or anything that might cause a mass to accelerate.

Students give example of cases where force is in action.

Assessments

At the end of the lesson ‘true or false’ questions will be made available to test students’ understanding of the topic

Students are also required to give situation or instances where Newton’s first law of motion is in action

Definition

Newton’s first law of motion states that:

Everybody or an object persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed

Or An object at rest tends to stay at rest and an

object in motion remains in motion unless acted on by an unbalanced force or a net force

The Newton’s first law of motion is also called the law of inertia

Illustration

Balanced and unbalanced forces (Class activity)

10N 25N10N 10N

Balanced and unbalanced forces

Which of the following is/are correct?

(a)An object in motion will slow down unless it is acted on by an unbalanced force in the direction of motion

(b)An object in motion will maintain its speed and direction forever unless acted on by an unbalanced force

(c)An object at rest will stay at rest unless acted on by an unbalanced force

(d)An object acted on by an unbalanced force will always accelerate in the direction of the of the unbalanced force

Explanation of balanced and unbalanced force

The diagram above is a ball with forces from four different dimensions acting on it. If for example all the forces are balanced, all of 5 Newton (5N) each, then the ball will remain at rest.

But in a case where the forces from certain direction are greater than the ones from the other direction, for example if the Newton of the forces varies, some are 5N and others are 15N; the body becomes unstable and moves in the direction of the greater force, either down, up, side, etcetera. The same is true for children playing on a swing.

Next lesson

Next class, we shall learn about Newton’s second law of motion.

Watch the following videos:https://www.khanacademy.org/science/physics/forces-newtons-laws/newtons-laws-of-motion/v/newton-s-1st-law-of-motion

https://www.khanacademy.org/science/physics/forces-newtons-laws/newtons-laws-of-motion/v/newton-s-second-law-of-motion

Team work

The work for this project was shared equally, working together eithyer physically or virtually (online).

Still work -in- progress