LEIS DE NEWTON - [FÍSICA DO ZERO]

Summary

This video covers Sir Isaac Newton's three laws of motion, explaining them in an easy-to-understand manner. The first law, the principle of inertia, describes how objects at rest stay at rest and objects in motion continue in motion unless acted upon. The second law, which is the force-mass-acceleration relationship, highlights how the force on an object determines its acceleration. The third law, action and reaction, explains how every action has an equal and opposite reaction. The video concludes with a simple example of applying these laws to solve a physics problem involving force and acceleration.

Takeaways

• 😀 Newton's First Law (Inertia) states that an object at rest will stay at rest, and an object in motion will stay in motion unless acted upon by an external force.
• 😀 An example of inertia: if you're driving a car and it suddenly stops, your body continues to move forward, which demonstrates inertia.
• 😀 In space, if a spaceship is in motion and its engines are turned off, it will continue moving indefinitely unless it collides with something due to inertia.
• 😀 Newton's Second Law (Force and Acceleration) is represented by the formula F = ma, where F is the force, m is the mass, and a is the acceleration.
• 😀 The greater the force applied to an object, the greater its acceleration (speed change). Conversely, if the mass of an object is greater, it accelerates less for the same force.
• 😀 The unit of force is the Newton (N), named after Sir Isaac Newton, and acceleration is measured in meters per second squared (m/s²).
• 😀 Newton's Third Law (Action and Reaction) explains that for every action, there is an equal and opposite reaction.
• 😀 An example of action and reaction: If you push a wall with a certain force, the wall pushes back with the same force in the opposite direction.
• 😀 Action and reaction forces occur simultaneously, with equal intensity but opposite direction, like when you jump off a boat, and the boat moves in the opposite direction.
• 😀 In solving physics problems, understanding the direction and magnitude of forces is crucial for calculating acceleration using the Second Law formula.
• 😀 When forces act in opposite directions (e.g., right and left), the net force is the difference between the forces, and this is used to calculate acceleration.

Q & A

What is the first law of Newton, and what does it describe?

The first law of Newton is known as the law of inertia. It states that an object at rest will remain at rest, and an object in motion will continue in motion at a constant velocity in a straight line unless acted upon by an external force.

Can you provide an example of Newton's first law involving a car?

Yes, for example, when you are in a car moving at 100 km/h and the car suddenly brakes, your body continues moving forward. This happens because of inertia, as your body wants to maintain the same motion as the car was initially in.

Why is the seatbelt important in terms of Newton's first law?

The seatbelt is important because, without it, if the car stops suddenly, your body would continue moving forward due to inertia. The seatbelt helps to prevent this by stopping your body from continuing its motion when the car halts.

How does Newton’s first law apply to an object moving in space?

In space, if a spaceship is moving and its engines are turned off, it will continue moving indefinitely in a straight line at constant speed because there is no air or friction to slow it down. This is a demonstration of the law of inertia.

What is the equation related to Newton’s second law, and what do the variables represent?

The equation for Newton's second law is F = m × a. 'F' represents the resultant force applied to an object, 'm' is the mass of the object, and 'a' is the acceleration of the object. This law describes how the force applied to an object is directly proportional to its acceleration.

What is meant by the term 'force resultant' in Newton's second law?

The force resultant is the total force acting on an object, considering all the individual forces applied to it. It is calculated by summing all the forces acting in different directions.

What is the unit of force in Newton's second law?

The unit of force is the Newton (N), named after Sir Isaac Newton, and it is defined as the amount of force needed to accelerate a 1-kilogram object by 1 meter per second squared.

How is the acceleration of an object affected by the force applied to it, according to Newton's second law?

According to Newton's second law, the greater the force applied to an object, the greater its acceleration, assuming the mass remains constant. The relationship between force and acceleration is directly proportional.

What is the third law of Newton, and how does it apply to actions and reactions?

Newton's third law is the principle of action and reaction, which states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on another, the second object exerts an equal and opposite force on the first.

What is a common misunderstanding of Newton's third law?

A common misunderstanding is that people think action and reaction are related to karma or a life principle, such as 'you reap what you sow.' However, in Newton's third law, action and reaction are simply two forces that occur simultaneously and are equal in magnitude but opposite in direction.