Class 9 Science – Gravitation (Easy Notes)
What is Gravitation?
Every object in the universe attracts every other object with a force called gravitational
force.
Newton’s Universal Law of Gravitation
F = G (m m / r )
Free Fall
When an object falls only under gravity.
Acceleration Due to Gravity (g)
g = 9.8 m/s on Earth.
Mass vs Weight
Mass = constant
Weight = mg
Pressure
Pressure = Force / Area
Numericals
1. Weight of 20 kg object:
W = 20 × 9.8 = 196 N
2. Force becomes 1/4 if distance doubles twice.
Exam Points
- Weight changes, mass does not.
- Pressure increases when area decreases.
- Gravity acts equally on all objects.
What is Gravitation?
Every object in the universe attracts every other object with a force called gravitational
force.
Newton’s Universal Law of Gravitation
F = G (m m / r )
Free Fall
When an object falls only under gravity.
Acceleration Due to Gravity (g)
g = 9.8 m/s on Earth.
Mass vs Weight
Mass = constant
Weight = mg
Pressure
Pressure = Force / Area
Numericals
1. Weight of 20 kg object:
W = 20 × 9.8 = 196 N
2. Force becomes 1/4 if distance doubles twice.
Exam Points
- Weight changes, mass does not.
- Pressure increases when area decreases.
- Gravity acts equally on all objects.
