It is independent of the mass of an object. In a vacuum, all objects, regardless of mass, accelerate at the same rate.
Close to the Earth, all freely falling objects accelerate downward towards the centre of the Earth with the same acceleration if we neglect the air resistance.
This acceleration is due to gravity which is approximately 10 m/s2 in value and denoted by g. It can be defined as:
The acceleration produced in the freely falling body due to the attraction of the earth is called acceleration due to gravity.
Experimental Measurement of g
We need a millisecond or centisecond timer, a metal ball, a trapdoor, an electromagnet, and metre rule to measure the value of g.
Set up the following apparatus. The centisecond or millisecond timer starts when the ball is released and stops when the ball hits the trapdoor.
The value of g can be calculated by using the following equation.
Different Names of g
At IGCSE level, we use two different names of "g".
- The gravitational field strength (N/kg)
- The acceleration due to gravity (m/s2)
The gravitational force acting on per unit mass of an object is known as gravitational field strength.
A mass of 10kg on the different planets has the same mass but it has different weight on each planet.
The gravitational field strength of moon is 1.6N/kg.The gravitational field strength of earth is 10N/kg.
The gravitational field strength of Jupiter is 27N/kg.
Conclusion
The gravitational field strength depends on the mass of the body (moon, planet, or stars). As Jupiter is the most massive planet in our solar system, so the value of gravitational field strength of Jupiter is about 27 N/kg.
