Physics - Term 2 - Week 1

Newton's First Law states that 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 a net external force. This principle highlights the concept of inertia, which is the tendency of objects to resist changes in their state of motion.

The Second Law of Motion establishes the relationship between force, mass, and acceleration, expressed by the formula F = ma. This means that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This law helps us understand how different forces affect the motion of objects.

Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that forces always occur in pairs; when one object exerts a force on another, the second object exerts a force of equal magnitude but in the opposite direction on the first object. This principle is crucial in understanding interactions between objects.

Consider a soccer ball lying on the ground. According to Newton's First Law, the ball will not move until a player kicks it. Once kicked, the ball will continue to roll until friction from the ground or another force stops it. This illustrates inertia and the need for a net external force to change the state of motion.

If a car with a mass of 1000 kg accelerates at 2 m/s², we can calculate the force applied using F = ma. Here, F = 1000 kg * 2 m/s², which gives us a force of 2000 N. This example shows how mass and acceleration relate to the force applied to an object.

When a swimmer pushes against the wall of a pool, they exert a force on the wall. According to Newton's Third Law, the wall exerts an equal and opposite force back on the swimmer, propelling them forward. This interaction demonstrates how action and reaction forces work in practice.

In pairs, students will observe a video of a car accelerating and discuss the forces acting on the car. They should identify the net force causing the acceleration and relate it to Newton's Second Law. Afterward, each pair will present their findings to the class, emphasizing the relationship between force, mass, and acceleration.

Students will complete a worksheet that includes various scenarios where they must identify which of Newton's laws apply. For example, they may analyze a skateboarder pushing off the ground or a book resting on a table. They will explain their reasoning and provide examples of real-life applications for each law.

• The relationship between force and mass
• The tendency of an object to resist changes in motion
• The action-reaction principle
• The acceleration of an object

Answer: The tendency of an object to resist changes in motion

Newton's First Law, also known as the law of inertia, states that an object will not change its state of motion unless acted upon by a net external force.

• F = ma
• F = mv
• F = m/a
• F = m + a

Answer: F = ma

Newton's Second Law is expressed as F = ma, where F is the net force, m is the mass, and a is the acceleration.

• The wall moves away from you
• You exert no force
• The wall pushes back with an equal force
• You fall backwards

Answer: The wall pushes back with an equal force

Newton's Third Law states that for every action, there is an equal and opposite reaction, meaning the wall exerts an equal force back on you.

Answer: Inertia is the tendency of an object to resist changes in its state of motion.

Inertia is a key concept in Newton's First Law, illustrating how objects remain at rest or in uniform motion unless acted upon by a force.

Answer: A car accelerating when the driver presses the gas pedal.

This example shows how the force applied by the engine causes the car to accelerate, demonstrating the relationship between force, mass, and acceleration.

• Kilogram
• Newton
• Joule
• Pascal

Answer: Newton

The unit of force in the SI system is the Newton (N), which is defined as the force required to accelerate a one-kilogram mass by one meter per second squared.