Lesson Notes By Weeks and Term - Junior Secondary 1

TERM – 3^RD TERM

WEEK FOUR

Class: Junior Secondary School 1

Age: 12 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC SCIENCE

Topic: CALCULATIONS OF GRAVITATIONAL FORCE

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. Differentiate between balanced and unbalanced force
2. Define friction
3. Identify the uses of friction
4. Identify the advantages and disadvantages of friction

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

CALCULATIONS OF GRAVITATIONAL FORCE

Balance Forces

- Balanced forces occur when the net force acting on an object is zero.

- When balanced forces act on an object, the object remains at rest or continues to move at a constant velocity (in a straight line with constant speed).

- In other words, balanced forces do not cause a change in the object's motion.

- Examples of balanced forces include a book sitting on a table (where the force of gravity pulling the book down is balanced by the normal force exerted by the table upward) and a car traveling at a constant speed on a straight road (where the driving force forward is balanced by the frictional force and air resistance backward).

Unbalanced Forces

- Unbalanced forces occur when the net force acting on an object is not zero.

- When unbalanced forces act on an object, they cause a change in the object's motion (acceleration).

- If unbalanced forces act in the same direction, they cause the object to accelerate in that direction.

- If unbalanced forces act in opposite directions, they result in a net force in one direction, causing the object to accelerate in that direction.

- Examples of unbalanced forces include pushing a box across a floor (where the applied force overcomes the force of friction, causing the box to accelerate) and a ball falling from a height (where the force of gravity downward is greater than the air resistance upward, causing the ball to accelerate downward).

Friction

Friction is a force that resists the relative motion or tendency of motion between two surfaces in contact. It arises due to the microscopic irregularities on the surfaces of objects, which interlock when in contact, causing resistance to motion. Friction acts parallel to the surfaces in contact and opposes the direction of motion or the applied force trying to cause motion.

Uses of friction

1. Friction between tires and the road surface provides traction, allowing vehicles to accelerate, decelerate, and maintain control during driving.
2. Friction is essential for braking systems in vehicles. The friction between brake pads and rotors slows down the vehicle when brakes are applied.
3. Friction helps in gripping surfaces, which is crucial in activities like rock climbing, holding tools, and playing sports.
4. Friction between the pen tip and paper allows for the transfer of ink, enabling writing and drawing.
5. Friction between the soles of shoes and the ground provides stability and prevents slipping while walking or running.

Advantages of friction

1. Friction allows for precise control over the motion of objects. For example, adjusting the amount of friction in machinery can regulate speed and prevent unwanted movements.
2. Friction generates heat, which is beneficial in various applications such as starting fires through frictional ignition (e.g., rubbing sticks together) and industrial processes like metalworking.
3. Friction helps prevent slipping and sliding, reducing the risk of accidents in various situations, including driving, walking, and handling objects.

Disadvantages of friction

1. Friction causes wear and tear on surfaces in contact, leading to deterioration of materials over time.
2. Friction results in the conversion of kinetic energy into heat energy, leading to energy loss in systems where friction is present.
3. Friction opposes motion, which can be a hindrance in some cases, such as in the movement of vehicles and machinery.

EVALUATION: 1. Differentiate between balanced and unbalanced force.

2. Mention 5 uses of friction.
3. What is friction?
4. Identify 5 advantages and 5 disadvantages of friction.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively