Mass versus weight - Wikipedia
From the above discussion we see that mass and weight cannot strictly with a relationship between mass and weight that is implicitly used whenever The upshot of all this is that the weight of an object is proportional to its inertial mass and. The relation between mass and weight of a body is defined by Newton's Second weight of an object is directly proportional to the value of gravity of that place. In common usage, the mass of an object is often referred to as its weight, though these are in While the weight of an object varies in proportion to the strength of the . the relationship between mass and weight on Earth is highly proportional; objects . scale at a doctor's office, they are having their mass measured directly.
Mass is among other properties an inertial property; that is, the tendency of an object to remain at constant velocity unless acted upon by an outside force.
- Planetary and Satellite Motion
- Mass and Weight
- Mass, weight and gravitational field strength
Inertia is seen when a bowling ball is pushed horizontally on a level, smooth surface, and continues in horizontal motion. This is quite distinct from its weight, which is the downwards gravitational force of the bowling ball one must counter when holding it off the floor. The weight of the bowling ball on the Moon would be one-sixth of that on the Earth, although its mass remains unchanged. Consequently, whenever the physics of recoil kinetics mass, velocity, inertia, inelastic and elastic collisions dominate and the influence of gravity is a negligible factor, the behavior of objects remains consistent even where gravity is relatively weak.
For instance, billiard balls on a billiard table would scatter and recoil with the same speeds and energies after a break shot on the Moon as on Earth; they would, however, drop into the pockets much more slowly. In the physical sciences, the terms "mass" and "weight" are rigidly defined as separate measures, as they are different physical properties.
In everyday use, as all everyday objects have both mass and weight and one is almost exactly proportional to the other, "weight" often serves to describe both properties, its meaning being dependent upon context.
For example, in retail commerce, the "net weight" of products actually refers to mass, and is expressed in mass units such as grams or ounces see also Pound: Conversely, the load index rating on automobile tires, which specifies the maximum structural load for a tire in kilograms, refers to weight; that is, the force due to gravity.
Before the late 20th century, the distinction between the two was not strictly applied in technical writing, so that expressions such as "molecular weight" for molecular mass are still seen. Because mass and weight are separate quantities, they have different units of measure. In the International System of Units SIthe kilogram is the basic unit of mass, and the newton is the basic unit of force. The non-SI kilogram-force is also a unit of force typically used in the measure of weight.
Similarly, the avoirdupois poundused in both the Imperial system and U. Converting units of mass to equivalent forces on Earth[ edit ] Gravity anomalies covering the Southern Ocean are shown here in false-color relief. This image has been normalized to remove variation due to differences in latitude. When an object's weight its gravitational force is expressed in "kilograms", this actually refers to the kilogram-force kgf or kg-falso known as the kilopond kpwhich is a non-SI unit of force.
All objects on the Earth's surface are subject to a gravitational acceleration of approximately 9. The General Conference on Weights and Measures fixed the value of standard gravity at precisely 9. Thus the kilogram-force is defined as precisely 9.
Mass and Weight - Definition, Relation, Difference & Effects of Gravity | [email protected]
In reality, gravitational acceleration symbol: If the distance is increased by a factor of 2, then distance squared will increase by a factor of 4. Therefore, the force of gravity becomes 4 units. Suppose the distance in question 1 is tripled.The Difference Between Mass and Weight
What happens to the forces between the two objects? Again using inverse square law, we get distance squared to go up by a factor of 9. The force decreases by a factor of 9 and becomes 1.
Mass versus weight
If you wanted to make a profit in buying gold by weight at one altitude and selling it at another altitude for the same price per weight, should you buy or sell at the higher altitude location? What kind of scale must you use for this work?
To profit, buy at a high altitude and sell at a low altitude. Explanation is left to the student. Check Your Understanding 4. Your weight is nothing but force of gravity between the earth and you as an object with a mass m.
As shown in the above graph, changing one of the masses results in change in force of gravity. The planet Jupiter is more than times as massive as Earth, so it might seem that a body on the surface of Jupiter would weigh times as much as on Earth. But it so happens a body would scarcely weigh three times as much on the surface of Jupiter as it would on the surface of the Earth.
Explain why this is so. The effect of greater mass of Jupiter is partly off set by its larger radius which is about 10 times the radius of the earth. This means the object is times farther from the center of the Jupiter compared to the earth. Inverse of the distance brings a factor of to the denominator and as a result, the force increases by a factor of due to the mass, but decreases by a factor of due to the distance squared. The net effect is that the force increases 3 times.
Planetary and Satellite Motion After reading this section, it is recommended to check the following movie of Kepler's laws. Kepler's three laws of planetary motion can be described as follows: Law of Orbits Kepler's First Law is illustrated in the image shown above. The Sun is not at the center of the ellipse, but is instead at one focus generally there is nothing at the other focus of the ellipse.
The planet then follows the ellipse in its orbit, which means that the Earth-Sun distance is constantly changing as the planet earth goes around its orbit. For purpose of illustration we have shown the orbit as rather eccentric; remember that the actual orbits are much less eccentric than this. Law of Areas Kepler's second law is illustrated in the preceding figure. The line joining the Sun and planet sweeps out equal areas in equal times, so the planet moves faster when it is nearer the Sun.
Thus, a planet executes elliptical motion with constantly changing angular speed as it moves about its orbit. The point of nearest approach of the planet to the Sun is termed perihelion; the point of greatest separation is termed aphelion.
Newton's Laws and Weight, Mass & Gravity - Video & Lesson Transcript | vifleem.info
Hence, by Kepler's second law, the planet moves fastest when it is near perihelion and slowest when it is near aphelion. Law of Periods In this equation P represents the period of revolution for a planet in some other references the period is denoted as "T" and R represents the length of its semi-major axis. The subscripts "1" and "2" distinguish quantities for planet 1 and 2 respectively.
The periods for the two planets are assumed to be in the same time units and the lengths of the semi-major axes for the two planets are assumed to be in the same distance units.
Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit. Thus, we find that Mercury, the innermost planet, takes only 88 days to orbit the Sun but the outermost planet Pluto requires years to do the same.
The Seasons There is a popular misconception that the seasons on the Earth are caused by varying distances of the Earth from the Sun on its elliptical orbit.
This is not correct. One way to see that this reasoning may be in error is to note that the seasons are out of phase in the Northern and Southern hemispheres: Seasons in the Northern Hemisphere The primary cause of the seasons is the This means that as the Earth goes around its orbit the Northern hemisphere is at various times oriented more toward and more away from the Sun, and likewise for the Southern hemisphere, as illustrated in the following figure.
Thus, we experience Summer in the Northern Hemisphere when the Earth is on that part of its orbit where the N. Hemisphere is oriented more toward the Sun and therefore the Sun rises higher in the sky and is above the horizon longer, and the rays of the Sun strike the ground more directly.
Likewise, in the N. The gravitational force increases as the size of an object increases. On the other hand, the strength of gravity is inversely related to the square of the distance between two objects. For example, if the distance between two objects doubles, meaning they're twice as far apart, the gravitational pull decreases by a factor of 4.
This is because 2 squared is equal to 4. This means the effect of distance on gravitational attraction is greater than the effect of the masses of the objects. Gravity as a Force Gravity is a force. A force is simply a push or a pull experienced by objects that interact with each other. The interaction can be direct or at a distance, which is the case of gravity. Newton's laws tell us that if an unbalanced force acts on an object, it will change the object's state of motion.
In other words, the object will accelerate. Since gravity is a force, gravity causes objects to accelerate. Acceleration Due to Gravity Let's look at an example of how gravity causes acceleration.