A piece of iron with a mass of 790 g displaces 100g of water when it sinks. What does the iron weigh in air and under water?

Asked by anusha | 10th Oct, 2013, 11:47: AM

Expert Answer:

The mass of iron piece is m = 790 g = 0.79 kg.
Acceleration due to gravity is ? 10 m/s2.
Thus, weight of iron in air is
 
Now, when immersed in water, it displaces 100 g of water and sinks.
Thus weight of water displaced by iron is
 
Now, the buoyant force on iron will be equal to the weight of the water displaced, that is, 1N.
 
Thus, weight of iron in water is
Wwater = Wair - W = 6.9 N

Answered by Romal Bhansali | 10th Oct, 2013, 12:41: PM

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