51. What is the mass of 4.2 kg of gold when it is transferred to a planet having twice the gravity of earth?
71. You have a mixture of salt and sand that must be separated by using physical changes only. Describe what you would do to prepare dry samples of the two constituents of the mixture.
51. To calculate the mass of 4.2 kg of gold on a planet with twice the gravity of Earth, you need to use the concept of weight. Weight is the force exerted on an object due to gravity. On Earth, the weight is calculated by multiplying the mass of an object by the acceleration due to gravity (which is approximately 9.8 m/s^2).
To find the weight on a planet with twice the gravity of Earth, you need to multiply the mass (4.2 kg) by twice the acceleration due to gravity (2 * 9.8 m/s^2).
So, the weight of 4.2 kg of gold on a planet with twice the gravity of Earth would be:
Weight = Mass x Acceleration due to gravity
Weight = 4.2 kg x (2 * 9.8 m/s^2)
You can now calculate the weight of the gold on the planet.
71. To separate a mixture of salt and sand using physical changes only, you can follow the process of filtration and evaporation.
1. Fill a beaker or any other container with water.
2. Add the mixture of salt and sand to the water and stir it well. This will cause the salt to dissolve in the water, while the sand will remain insoluble.
3. Set up a filtration apparatus or use a simple filter paper placed on top of a funnel.
4. Pour the mixture into the funnel and let the water pass through, collecting the sand in the filter paper. The saltwater solution will pass through into the receiving container.
5. Now, you have separated the sand from the saltwater solution.
6. To obtain dry samples of the two constituents, you can perform evaporation. Pour the saltwater solution into an evaporating dish or a shallow container.
7. Place the evaporating dish on a hot plate or in the sun to allow the water to evaporate, leaving the salt behind.
8. Once all the water has evaporated, you will be left with dry salt in the dish. This is one of the separated constituents.
9. To collect the dry sand, simply remove it from the filter paper and allow it to air dry or use a separate drying method if necessary.
By following these steps, you can successfully separate the salt and sand from the mixture using physical changes only.