Physics - Term 2 - Week 7

Newton's first law states that an object at rest stays at rest, and an object in motion continues in motion with the same speed and in the same direction unless acted upon by a net external force. This principle is often referred to as the law of inertia. The second law quantifies the relationship between force, mass, and acceleration, expressed by the formula F = ma, where F is the net force applied to an object, m is its mass, and a is the acceleration produced. Finally, Newton's third law states that for every action, there is an equal and opposite reaction, meaning that forces always occur in pairs.

Consider a scenario where two forces are acting on a box: a 10 N force to the right and a 5 N force to the left. To find the net force, we subtract the opposing forces: 10 N - 5 N = 5 N to the right. This net force will cause the box to accelerate in the direction of the net force according to Newton's second law.

In pairs, students will observe their surroundings and identify examples of Newton's laws in action. For instance, they can discuss how a soccer ball remains stationary until kicked (first law), how a heavier object requires more force to move (second law), and how when they push against a wall, the wall pushes back with equal force (third law). Each pair will share their findings with the class.

Students will complete a worksheet that includes various problems related to forces and motion. They will calculate net forces in different scenarios, apply Newton's laws to predict motion, and provide explanations for their reasoning. This will reinforce their understanding and application of the concepts learned in class.

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

Answer: The tendency of objects to resist changes in their state of motion

Newton's first law, also known as the law of inertia, states that an object will remain at rest or in uniform motion unless acted upon by a net external force.

• 2 N
• 5 N
• 10 N
• 15 N

Answer: 10 N

Using Newton's second law (F = ma), the net force is calculated as F = 5 kg * 2 m/s² = 10 N.

Answer: For every action, there is an equal and opposite reaction.

This law indicates 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.

• A ball rolling down a hill
• A car accelerating when the gas pedal is pressed
• A book resting on a table
• A rocket launching into space

Answer: A car accelerating when the gas pedal is pressed

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

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

Inertia is directly related to mass; the greater the mass of an object, the greater its inertia.

• A car speeding up on a highway
• A soccer ball remaining still until kicked
• A person pushing a shopping cart
• A rocket moving in space

Answer: A soccer ball remaining still until kicked