Technical Science - Term 1 - Week 3

A force is a push or pull acting upon an object as a result of its interaction with another object. Forces can cause an object to start moving, stop moving, or change direction. The unit of force is the Newton (N), and it is a vector quantity, meaning it has both magnitude and direction. Common forces include gravitational force, frictional force, and tension.

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. The second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma). The third law states that for every action, there is an equal and opposite reaction.

Consider a car with a mass of 1,000 kg that accelerates at 2 m/s². To find the net force acting on the car, we use the formula F = ma. Here, F = 1,000 kg * 2 m/s² = 2,000 N. This means a net force of 2,000 Newtons is required to accelerate the car at this rate.

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 in the water. This interaction illustrates how action and reaction forces work in practice.

Let's work through a problem together. A bicycle with a mass of 15 kg accelerates at 3 m/s². What is the net force acting on the bicycle? Using F = ma, we calculate F = 15 kg * 3 m/s² = 45 N. Now, can anyone explain what this force represents in terms of the bicycle's motion?

In pairs, discuss the forces acting on a book resting on a table. Identify the gravitational force pulling it down and the normal force from the table pushing it up. How do these forces balance each other? Share your findings with the class.

Now it's your turn! Solve the following problems on your own: 1) A 5 kg object is pushed with a force of 20 N. What is its acceleration? 2) If a car weighing 1,200 kg experiences a net force of 3,600 N, what is its acceleration? Write down your answers and be prepared to discuss them in the next class.

Think of a scenario in your daily life where you can observe Newton's laws in action. Write a short paragraph describing the situation, the forces involved, and how the laws apply. Be ready to share your example with the class.

• Joule
• Newton
• Pascal
• Watt

Answer: Newton

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

• An equal force
• A net external force
• Friction
• Gravity

Answer: A net external force

Newton's first law states that an object will maintain its state of motion unless a net external force acts on it.

• Force and mass
• Mass and velocity
• Force and acceleration
• Acceleration and distance

Answer: Force and acceleration

Newton's second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

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

This law explains that forces always occur in pairs; when one object exerts a force on another, the second object exerts a force of equal magnitude in the opposite direction.

• 50 N
• 10 N
• 15 N
• 20 N

Answer: 50 N

Using F = ma, the net force is calculated as F = 10 kg * 5 m/s² = 50 N.

Answer: A soccer ball remains at rest until a player kicks it.

This example illustrates that an object at rest will not move unless acted upon by an external force.