The planet Jupiter is about 11 times the diameter of the Earth - Jupiter has a large enough volume that approximately 1,300 Earths could fit inside it!

Jupiter has a stronger force of gravity than Earth. Let's learn about how **weight **can vary from planet to planet!

The Earth has a gravitational field strength of 9.8 N/kg. The force of gravity is what causes objects to have **weight. **We can calculate the weight of an object with this equation:

**Weight (N) = Mass (kg) × Gravitational Field Strength (N/kg)**

W (N) = m (kg) × g (N/kg)

Calculating weight can become a bit more complicated when you look at situations where the **gravitational field strength **is different, like on other planets.

Let's look back at Jupiter.

The **gravitational field strength **of Jupiter is 24.7 N/kg. In other words, gravity on the surface of Jupiter would be about 2.4 times greater than the gravity we experience on Earth.

**Example **

How much would a 2.4 kg laptop weigh on Jupiter?

__Answer__

Weight (N) = 2.4 kg × 24.7 N/kg = 59.28 N

That same laptop would weigh 23.52 N on Earth. Remember, the **mass **of the object is constant because mass is a measure of how much material an object is made up of. The **weight **of an object depends on the gravitational field strength it experiences, so the weight of an object depends on where it is in space!

Mars is a smaller planet than the Earth. The diameter of Mars is about half the diameter of Earth, and the mass of Mars is only about 10% of the mass of the Earth. What do you think the gravitational field strength on Mars might be, compared to Earth?

The gravitational field strength on Mars is 3.71 N/kg. You might have predicted that the gravity on Mars would be less than the 9.8 N/kg we are used to!

__Example__

How much would a 4 kg box on Mars weigh?

**Answer**

Weight (N) = 4 kg × 3.71 N/kg = 14.84 N

That same box on Earth would weigh 39.2 N!

Now let's see if we can figure out the **gravitational field strength **of a planet, using the mass of an object and its weight!

We can **rearrange **the equation for weight to make gravitational field strength the subject. We do this by **dividing **both sides of the equation by** mass. **

Then the mass on the right-hand side cancels out, and we can re-write the equation like this:

**Example**

** **A saxophone has a mass of 3 kg. On a different planet, it has a weight of 1.86 N. What is the gravitational field strength of the planet?

**Answer**

g (N/kg) = 1.86 N ÷ 3 kg

g (N/kg) = 0.62 N/kg

That's the gravitational field strength of Pluto - a **dwarf **planet in our Solar System.

Now let's try some questions!