Physics - Term 3 - Week 1

Newton's first law states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity unless acted upon by a net external force. This principle highlights the concept of inertia. The second law quantifies the relationship between force, mass, and acceleration, expressed by the formula F = ma. The third law states that for every action, there is an equal and opposite reaction, indicating 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: Net Force = 10 N (right) - 5 N (left) = 5 N to the right. This example illustrates how to determine the overall effect of multiple forces acting on an object.

In pairs, students will observe a variety of scenarios around the classroom, such as a book resting on a table, a ball rolling on the floor, and a person pushing a shopping cart. They will identify the forces acting on each object, discussing factors like gravity, friction, and applied forces. This activity encourages collaboration and reinforces the application of Newton's laws in real-world situations.

Students will complete a worksheet that includes problems requiring them to calculate net forces in different scenarios. For example, they may be asked to determine the net force on a sled being pulled with a force of 30 N to the right while experiencing a frictional force of 10 N to the left. This independent practice will help solidify their understanding of the concepts discussed in class.

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

Answer: The tendency of objects to resist changes in motion.

Newton's first law, also known as the law of inertia, states that objects will not change their state of motion unless acted upon by a net external force.

• 2 m/s²
• 4 m/s²
• 5 m/s²
• 10 m/s²

Answer: 4 m/s²

Using Newton's second law (F = ma), we can rearrange it to find acceleration: a = F/m = 20 N / 5 kg = 4 m/s².

• A car accelerating down a hill.
• A rocket launching into space.
• A ball rolling on the ground.
• A book resting on a table.

Answer: A rocket launching into space.

When a rocket expels gas downwards, it experiences an equal and opposite force that propels it upwards, illustrating Newton's third law.

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

Inertia is a fundamental concept in physics that explains why objects remain at rest or in uniform motion unless acted upon by an external force.

Answer: 0 N

When equal forces act in opposite directions, they cancel each other out, resulting in a net force of zero.

• It accelerates.
• It remains at rest or continues moving at a constant velocity.
• It stops immediately.
• It changes direction.

Answer: It remains at rest or continues moving at a constant velocity.