The radius of the planet Venus is nearly the same as that of the earth, but its mass is only 80% that of the earth, if an object weighs we on the earth, what does it weighs on Venus?

f = G M m / r^2

if one of the masses is only 80% , then the force (weight) will be 80%

I still don't understand

To determine the weight of an object on Venus, knowing that Venus has a radius similar to Earth's and its mass is only 80% that of Earth's, we can use the formula for weight:

Weight = mass * gravitational acceleration

The gravitational acceleration on Venus can be calculated using the equation:

gravitational acceleration on Venus = (gravitational constant * mass of Venus) / (radius of Venus)^2

Similarly, the gravitational acceleration on Earth is given by:

gravitational acceleration on Earth = (gravitational constant * mass of Earth) / (radius of Earth)^2

Since the radius of Venus is nearly the same as that of Earth, we can assume that the gravitational constant (G) is the same for both planets.

Now, let's find the weight of the object on Venus. Let's call the weight on Earth "W(subscript E)", and the weight on Venus "W(subscript V)".

W(subscript E) = mass of object * gravitational acceleration on Earth
W(subscript V) = mass of object * gravitational acceleration on Venus

Since the mass of the object remains the same, we will compare the weights using the ratio of the gravitational accelerations:

W(subscript V) / W(subscript E) = gravitational acceleration on Venus / gravitational acceleration on Earth

Substituting the values we have:

W(subscript V) / W(subscript E) = (gravitational constant * mass of Venus) / (radius of Venus)^2 / (gravitational constant * mass of Earth) / (radius of Earth)^2

Simplifying:

W(subscript V) / W(subscript E) = (mass of Venus * (radius of Earth)^2) / (mass of Earth * (radius of Venus)^2)

Since the radius of Venus is nearly the same as that of Earth:

W(subscript V) / W(subscript E) ≈ (mass of Venus) / (mass of Earth)

Given that the mass of Venus is only 80% (0.8) of the mass of Earth, we can conclude that an object weighing "W" on Earth would weigh approximately 80% of that value on Venus, which can be expressed as 0.8W.