Technical Science - Term 1 - Week 5

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 is often referred to as the law of inertia. It highlights the concept that forces are necessary to change the state of motion of an object.

Newton's Second Law quantifies the relationship between force, mass, and acceleration. It can be expressed with the formula F = ma, where F is the net force applied to an object, m is the mass of the object, and a is the acceleration produced. This law explains how the velocity of an object changes when it is subjected to an external force.

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 a second object, the second object exerts a force of equal magnitude but in the opposite direction back on the first object. This principle is crucial in understanding interactions between objects.

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

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 illustrates how forces work in pairs.

Let's work together on a problem. A bicycle with a mass of 15 kg accelerates at 3 m/s². What is the net force acting on the bicycle? Use the formula F = ma. First, identify the mass (m = 15 kg) and acceleration (a = 3 m/s²). Now calculate the force: F = 15 kg * 3 m/s² = 45 N. Therefore, the net force is 45 Newtons.

Now it's your turn! Solve the following problems on your own: 1) A 5 kg object is accelerated at 4 m/s². Calculate the force. 2) If a 10 kg object is at rest and a 30 N force is applied, what will be its acceleration? Show your calculations and reasoning.

• The relationship between force and mass
• The concept of inertia
• The action-reaction principle
• The acceleration of an object

Answer: The concept of inertia

Newton's First Law describes how an object will remain at rest or in uniform motion unless acted upon by a net external force, which is the essence of inertia.

• 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
• You fall backward
• The wall pushes back with equal force
• Nothing happens

Answer: The wall pushes back with 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 fundamental property of matter that describes how objects behave when forces are applied.

Answer: 5 m/s²

Using F = ma, we rearrange to find a = F/m. Thus, a = 10 N / 2 kg = 5 m/s².

• They are all balanced
• They are unbalanced
• They are zero
• They are increasing

Answer: They are balanced

If an object is in motion and not accelerating, the net forces acting on it must be balanced.