Final answer:
The weight of a 6 kg dog on a planet with double Earth's diameter and one-third Earth's mass would be calculated by considering the gravitational force changes. It would weigh one-third due to the mass and one-quarter due to the doubled radius, totaling a factor of 1/12 of its Earth weight, thus weighing only 0.5 kg.
Step-by-step explanation:
If a 6 kg dog were on or near the surface of a planet with double the Earth's diameter and one-third the Earth's mass, we would need to calculate the gravitational pull on the dog. The weight of an object on a planet is determined by the gravitational force which is dependent on the mass of the planet and the distance from the center of the planet to the object (the radius).
First, let's look at the effect of the change in mass of the planet. If the mass of the planet is one-third that of the Earth's mass, the gravitational force would reduce by a factor of 1/3, meaning the object would weigh one-third what it does on Earth.
Next, let's assess the impact of the increased diameter. With double the Earth's diameter, the radius would also double, which means the gravitational force at the surface would be reduced by a factor of (1/2)², or 1/4, due to the inverse square law of gravitation.
To find the overall effect on weight, we multiply these factors: (1/3) * (1/4) = 1/12. So, the 6 kg dog would weigh 6 kg / 12 = 0.5 kg on this hypothetical planet.
Therefore, the dog's weight would be significantly reduced due to the lower mass and larger radius of the planet in comparison to Earth.