Weight and Mass are Not the Same

Flipping Physics
10 Nov 201405:45
EducationalLearning
32 Likes 10 Comments

TLDRThis educational video script delves into the nuanced differences between weight and mass, clarifying common misconceptions. It explains that mass, measured in kilograms, is a scalar quantity and an intrinsic property of an object, while weight, measured in Newtons, is a vector quantity dependent on the force of gravity. The script uses examples from NASA, Michio Kaku's book, and YouTube videos to illustrate how weight is often incorrectly used to mean mass. It emphasizes that while mass remains constant across different planets, weight varies with the gravitational force exerted on the object.

Takeaways
  • 📏 Weight and mass are not the same; they are often confused but represent different physical concepts.
  • 📐 The base SI unit for mass is kilograms, while for weight (force), it is Newtons.
  • 🌍 Weight is the force of gravity acting between the Earth and an object, making it dependent on location.
  • 🔽 Weight is a vector quantity, having both magnitude and direction (downward), whereas mass is a scalar, with only magnitude.
  • 🚀 Mass is an intrinsic property of an object and does not change regardless of location, while weight can vary with gravity.
  • 🌕 On Earth, the acceleration due to gravity (g) is approximately 9.81 meters per second squared.
  • 🌕🌑 On the moon, the weight of an object is 1/6th of its weight on Earth due to the lower gravity.
  • 📚 The media sometimes incorrectly uses weight and mass interchangeably, even using kilograms to describe weight.
  • 🧠 Understanding the distinction between weight and mass is important for accurate scientific communication and comprehension.
  • 🛰️ Future space travel and living may make the difference between weight and mass more apparent to the general public.
Q & A

  • What is the base SI unit for mass?

    -The base SI unit for mass is the kilogram.

  • Is weight the same as mass?

    -No, weight and mass are not the same. Weight is the force of gravity acting on an object, while mass is a measure of the amount of matter in an object.

  • What is the SI unit for force?

    -The SI unit for force is the Newton.

  • How is a Newton defined in base SI dimensions?

    -A Newton is defined as a kilogram meter per second squared (1 kg·m/s²).

  • Why do people sometimes confuse weight and mass?

    -People often confuse weight and mass because they are used interchangeably in everyday language, even though they have different physical meanings.

  • Is weight a scalar or a vector quantity?

    -Weight is a vector quantity because it has both magnitude and direction (downward due to gravity).

  • Does an object's mass change when it is on a different planet?

    -No, an object's mass does not change when it is on a different planet. Mass is an intrinsic property of an object and is constant regardless of location.

  • How does the acceleration due to gravity affect weight?

    -Weight is calculated as the product of an object's mass and the acceleration due to gravity (W = m·g). Therefore, changes in the acceleration due to gravity will result in changes in weight.

  • What is the standard acceleration due to gravity on Earth?

    -The standard acceleration due to gravity on Earth is approximately 9.81 meters per second squared (9.81 m/s²).

  • How would the weight of a 70 kg person change on the moon?

    -On the moon, a person with a mass of 70 kg would weigh about 110 Newtons or approximately 26 pounds, which is less than their weight on Earth due to the moon's lower acceleration due to gravity.

  • What is the range of variation for the acceleration due to gravity on Earth's surface?

    -The acceleration due to gravity varies only slightly on Earth's surface, ranging from 9.78 to 9.83 meters per second squared (9.78 to 9.83 m/s²).

  • How might the common understanding of weight and mass change in the future?

    -With the potential for space travel and living in different gravitational environments becoming more common, people may become more aware of the distinction between weight and mass as they experience changes in weight due to different gravitational forces.

Outlines
00:00
📚 Understanding Weight vs Mass

This paragraph discusses the fundamental differences between weight and mass. It clarifies that while weight and mass are often used interchangeably, they are distinct concepts. Mass is a measure of the amount of matter in an object and is measured in kilograms, the base SI unit for mass. Weight, on the other hand, is the force of gravity acting on an object and is measured in Newtons, which are equivalent to a kilogram meter per second squared. The paragraph also highlights that weight is a vector quantity, having both magnitude and direction, while mass is a scalar, having only magnitude. Additionally, it points out that weight can change when one moves to a different planet due to varying gravitational forces, whereas mass remains constant as it is an intrinsic property of the object. The discussion includes references to common misconceptions in the media and scientific literature, emphasizing the importance of using the correct terminology.

05:00
🚀 The Future of Weight and Mass Perception

The second paragraph envisions a future where the common confusion between weight and mass might be reduced. It suggests that with advancements such as space elevators, people will experience changes in gravity and, consequently, in weight more frequently. This could lead to a better understanding and distinction between the concepts of weight and mass. The paragraph ends on a hopeful note, looking forward to a time when the variations in gravitational force will be a regular part of human experience, potentially enhancing the public's comprehension of these physical properties.

Mindmap
Keywords
💡Weight
Weight refers to the force of gravity acting upon an object. It is the measure of the attraction between the Earth and the object, and is quantified in Newtons. In the video, it is emphasized that weight is not the same as mass, and it changes depending on the gravitational field of the celestial body an object is on. For instance, a person's weight on Earth is about 690 Newtons if they have a mass of 70 kilograms, but this weight would reduce to about 110 Newtons on the moon due to the moon's lower gravitational pull.
💡Mass
Mass is a measure of the amount of matter in an object and is an intrinsic property, meaning it does not change regardless of location. It is quantified in kilograms and remains constant whether on Earth or any other celestial body. The video clarifies that mass is different from weight, as it does not vary with location, whereas weight does.
💡Gravity
Gravity is the force that attracts two bodies towards each other, and in the context of the video, it is specifically the Earth's gravitational pull on objects. The acceleration due to gravity, often denoted as 'g', is a constant on Earth's surface (approximately 9.81 meters per second squared) and determines the weight of an object based on its mass.
💡Newton
A Newton is the SI unit of force, which is used to quantify weight. It is defined as the force required to accelerate a one-kilogram mass by one meter per second squared. The video emphasizes that a Newton is distinct from a kilogram, which is the unit of mass, and that weight is expressed in Newtons, not kilograms.
💡SI Units
The International System of Units (SI) is the modern form of the metric system, and it is the most widely used system of measurement. The base SI unit for mass is the kilogram, and for force, it is the Newton. The video uses these units to distinguish between mass and weight, highlighting that they are measured differently within the SI system.
💡Vector
A vector is a quantity that has both magnitude and direction. In the context of the video, weight is described as a vector because it has a specific magnitude (measured in Newtons) and always points towards the center of the Earth due to gravity's pull.
💡Scalar
A scalar is a quantity that has magnitude but no direction. Mass is an example of a scalar quantity because it only has a magnitude (measured in kilograms) and does not involve direction. The video emphasizes this distinction to clarify that mass and weight are fundamentally different properties.
💡Intrinsic Property
An intrinsic property is a characteristic of an object that is inherent to it and does not depend on the object's location or any external factors. In the video, mass is described as an intrinsic property because it is a fundamental attribute of an object that remains constant regardless of where the object is.
💡Extrinsic Property
An extrinsic property is a characteristic that depends on external factors or the context in which an object is situated. In the video, weight is described as an extrinsic property because it varies depending on the gravitational field of the celestial body where the object is located.
💡Acceleration Due to Gravity
Acceleration due to gravity is the rate at which an object accelerates towards the Earth when it is in free fall, ignoring air resistance. It is a constant value on Earth's surface (approximately 9.81 meters per second squared) and is used in the calculation of weight. The video highlights that this value is what makes weight and mass often used interchangeably on Earth, as the slight variations in 'g' are negligible in everyday experiences.
💡Space Elevators
Space elevators are hypothetical structures that would provide a direct path from the Earth's surface to space, eliminating the need for conventional rocket launches. The video mentions the concept of space elevators as a future technology that could allow people to experience changes in the acceleration due to gravity as they travel up to and down from space stations, potentially leading to a clearer understanding of the difference between weight and mass.
Highlights

Weight and mass are not the same but often used interchangeably.

The base SI unit for mass is kilograms.

Weight is also known as the force of gravity, representing the attraction between Earth and an object.

Weight is a force and has the dimensions of force.

The SI unit for force is the Newton.

One Newton equals one kilogram meter per second squared.

Mass is measured in kilograms, while weight is measured in Newtons.

Weight given in kilograms in the media is technically incorrect.

Examples of incorrect weight usage in media include NASA's description of the Saturn V rocket and Michio Kaku's reference to Earth's weight.

Weight is a vector with both magnitude and direction, whereas mass is a scalar with only magnitude.

Mass is an intrinsic property, while weight is an extrinsic property.

The weight of an object depends on its mass and the acceleration due to gravity.

The acceleration due to gravity on Earth is approximately 9.81 meters per second squared.

An object's mass remains constant while its weight changes when on different celestial bodies.

On the moon, an object that weighs 70 kilograms on Earth would weigh about 26 pounds.

The almost constant value of Earth's gravity leads to the frequent interchangeability of weight and mass in everyday language.

The variation in Earth's gravity is minimal, ranging from 9.78 to 9.83 meters per second squared.

The dream of space elevators and the experience of changing gravity could lead to better understanding of weight and mass differences.

Transcripts

Browse More Related Video

Difference between MASS and WEIGHT

GCSE Physics Revision "Gravity and Weight"

Weight, Force, Mass & Gravity | Forces & Motion | Physics | FuseSchool

What is Mass Vs. Weight in Physics? - [1-5-11]

Are Mass and Weight the same thing? | Physics | Don't Memorise

Physics - What Is The Difference Between Mass and Weight?

Rate This

5.0 / 5 (0 votes)

Thanks for rating:

Related Tags
PhysicsEducationWeightVsMassMetricSystemGravityInfluenceSpaceTravelScientificMistakesEducationalContentInteractiveDiscussionPhysicsFundamentalsMedia Misconceptions