To determine which planet an object would weigh the most on, we need to consider the gravitational force on each planet. The weight of an object on a planet is directly related to the mass of the planet and inversely related to the square of its radius.
Since the problem states that we are assuming the planets are similar in radius, we can focus solely on the estimated mass of each planet. The weight of an object on a planet can be estimated by the mass of the planet.
Let's summarize the estimated masses given:
- Planet W: 6.4 x 10^23 kg
- Planet X: 3.3 x 10^23 kg
- Planet Y: 59.7 x 10^23 kg
- Planet Z: 48.7 x 10^23 kg
Among these, planet Y has the largest mass (59.7 x 10^23 kg). Therefore, an object would weigh the most on planet Y.
So the correct response is: on planet Y.