Library / Foundations: Physics / FPH-04
Foundations: Physics
Weight
Gravitational force on a mass.
- Ref
- FPH-04
- Rev
- v1
- Field
- Foundations: Physics
- Result
- W [N]
Near Earth, g is about 9.8 N/kg. Use the value given in the question. Mass is in kg and weight in newtons.
Weight is the pull of gravity on an object; heavier objects and stronger gravity give a bigger weight.
Calculator
N
kg
N/kg
- Weight on the Moon (1.62 N/kg)113.4 N
- Weight in kgf70.02 kgf
What drives the result
Each variable is moved across its typical range while the others stay at the values above. The longest bar is the key driver.
Weight (N) current value 686.7 N
mMassKey driver
9.819,810
gGravitational field strength
1121,750
- Mass stays the same everywhere, but weight depends on the local field.
- Weighing scales measure force but are labelled in kg.
Chart data as tables
Ranked variables
| Variable | Typical range | Lowest result | Highest result | Swing (N) | Local step | Change in result |
|---|---|---|---|---|---|---|
| m Mass | 1 to 1,000 kg | 9.81 | 9,810 | 9,800 | +10% | +10 % |
| g Gravitational field strength | 1.6 to 25 N/kg | 112 | 1,750 | 1,638 | +10% | +10 % |
Sweep of Mass
| Mass (kg) | Weight (N) |
|---|---|
| 1 | 9.81 |
| 2.371 | 23.26 |
| 5.623 | 55.17 |
| 13.34 | 130.8 |
| 31.62 | 310.2 |
| 74.99 | 735.6 |
| 177.8 | 1,744 |
| 421.7 | 4,137 |
| 1,000 | 9,810 |
Sweep one variable
Weight (N)Hover, touch, or use the arrow keys on the chart
Variables and how each one contributes
W
Weight
What the equation gives you. Everything else feeds it.
m
Mass
Mass of the object. Directly proportional.
g
Gravitational field strength
9.81 on Earth, 1.6 on the Moon. Directly proportional.
Worked example with the values above
- Mass 70 kg, g = 9.81 N/kg.
- Multiply: 70 × 9.81.
- W = 686.7 N.
Assumptions and limits
- Uniform gravitational field.
- Mass in kilograms.
Common mistakes
- Calling kg a unit of weight.
- Using grams.
Statistics and uncertainty
The standard value of g varies by about 0.5% over Earth’s surface, which is usually smaller than mass-measurement error.
Where it is used
- Load on supports and lifting gear.
- Starting point for energy and pressure problems.
Maths you need
- Mass: amount of matter
- Newton: unit of force