Edexcel IGCSE Physics: Double Science 复习笔记: 8.1.2 Gravitational Field Strength

Edexcel IGCSE Physics: Double Science 复习笔记: 8.1.2 Gravitational Field Strength

Gravitational Field Strength

 

  • The strength of gravity on different planets after an object's weight on that planet
  • Weight is defined as:

 

The force acting on an object due to gravitational attraction

  • Planets have strong gravitational fields
    • Hence, they attract nearby masses with a strong gravitational force

     

  • Because of weight:
    • Objects stay firmly on the ground
    • Objects will always fall to the ground
    • Satellites are kept in orbit

     

 

 

5-1-4-weight-force

Objects are attracted towards the centre of the Earth due to its gravitational field strength

 

 

 

  • Both the weight of any body and the value of the gravitational field strength g differs between the surface of the Earth and the surface of other bodies in space, including the Moon because of the planet or moon's mass
    • The greater the mass of the planet then the greater its gravitational field strength
    • A higher gravitational field strength means a larger attractive force towards the centre of that planet or moon

     

  • g varies with the distance from a planet, but on the surface of the planet, it is roughly the same
  • However, the value of g varies dramatically for different planets and moons
  • The gravitational field strength (g) on the Earth is approximately 10 N/kg
  • The gravitational field strength on the surface of the Moon is less than on the Earth
    • This means it would be easier to lift a mass on the surface of the Moon than on the Earth

     

  • The gravitational field strength on the surface of the gas giants (eg. Jupiter and Saturn) is more than on the Earth
    • This means it would be harder to lift a mass on the gas giants than on the Earth

     

 

3.1.1.6-gravitational-field-strength-diagram

 

Value for g on the different objects in the Solar System

 

 

 

  • On such planets such as Jupiter, an object’s mass remains the same at all points in space
  • However, their weight will be a lot greater meaning for example, a human will be unable to fully stand up

 

 

13.1.1.1-gravitational-field-strength

 

A person’s weight on Jupiter would be so large a human would be unable to fully stand up

 

 

Exam Tip

You do not need to remember the value of g on different planets for your exam, the value of g for Earth will be given in the exam question.

转载自savemyexams

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