Why g=9.8

That is the force of gravity follows inverse square law. Where G is the proportionality constant. It has the value 6. What does it mean to say that the gravity of the Earth is 9. Ed Hitchcock. Jan 27, Explanation: As per Law of Universal Gravitation the force of attraction between two bodies is directly proportional to the product of masses of the two bodies. Related questions Does gravitational force get weaker with distance? How strong is gravitational force? How does cosmic background radiation change the universe?

So most people just use 9. Example: how much force to hold an apple with a mass of 0. We also say the apple has a weight of 0. Example: a kg steel beam sits evenly on two supports. How much force is on each support? Gravity : the attraction of objects with mass or energy towards each other. Example: An Apple and the Earth The apple has a mass of 0. Example continued : Knowing the force is 0.

The Moon orbits the Earth at about , km every Connect and share knowledge within a single location that is structured and easy to search. You can go a few miles up or down and it'll still be good enough, but once you get any significant distance away from the surface of Earth, you would need to use a different value for gravitational acceleration.

How much does the acceleration of gravity change? Depending on the mass distribution and the shape not perfectly spherical! The approximation of 9. The exact value is most likely different at a specific location, due to the distance from the centre of the earth to the point being evaluated. The reference to "surface of the earth" is also a relative since the earth is known not to be perfectly round due to centrifugal forces making the radius greater at the equator.

Also, since the earth is spinning the same centrifugal forces have a slight influence on object mass at the evaluation point. Acceleration due to gravity, g is not a universal constant like G. Its calculated by formula mentioned in previous answers. The relation: Increase the height, g will become less as per formula.

The value 9. When height is small with respect to radius of earth , the value is slightly less than 9. So, this variation can be neglected for a high school etc problems. When accuracy is important due to scientific reasons etc , the value of g can't be 9. Once again, This consideration is valid only for constant mass system.

As we go above or below the surface of earth the value of g decreases since g is inversely proportional to height.