No, acceleration due to gravity is not absolutely constant, but for many practical purposes, it can be treated as such.
Understanding Acceleration Due to Gravity (g)
Acceleration due to gravity, often denoted as 'g', is the acceleration experienced by objects due to the gravitational force. While the average value of g is often cited as 9.81 m/s², this is an approximation.
Factors Affecting the Value of 'g'
Several factors cause variations in the value of 'g':
- Altitude: As you move further away from the Earth's surface, the gravitational force decreases, and hence 'g' decreases.
- Latitude: The Earth is not a perfect sphere; it bulges at the equator. This means that the distance to the Earth's center varies with latitude, affecting 'g'.
- Local Geology: Variations in the density of the Earth's crust can cause local variations in the gravitational field.
Practical Applications
According to the provided reference, "for practical purposes we take acceleration due to gravity as a constant". This is a useful simplification when:
- The distance between the body and the surface of the Earth is very small compared to the Earth's average radius.
- High precision is not required in calculations.
Example: Calculating the time it takes for an object to fall a few meters. In this case, assuming 'g' is constant (9.81 m/s²) will give a reasonably accurate result.
When 'g' Cannot Be Considered Constant
In situations demanding high accuracy or involving significant changes in altitude, we must consider the variations in 'g'. Examples include:
- Satellite Orbit Calculations: The gravitational field experienced by a satellite varies significantly depending on its altitude.
- Precise Geodetic Surveys: Accurate mapping and surveying require precise measurements of the gravitational field.
Summary
| Aspect | Description |
|---|---|
| Average Value of 'g' | 9.81 m/s² (on the Earth's surface) |
| Factors Causing Variation | Altitude, Latitude, Local Geology |
| Practical Application | Can be considered constant for small distances and when high precision is not required. |
| When Variation is Important | Satellite orbits, precise geodetic surveys, and other applications requiring high accuracy and considering significant changes in altitude |
