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Help with floatation and displacement in water

I know I should understand this but for the first time testing my own ideas it doesn't make sense.

I weigh an object on scales and find it to be 150g. I place this into a measuring container holding water and it floats. The water level rises by 150cm3.

Similarly

I weigh an object on scales and find it to be 100g. I place this into a measuring container holding water and it floats. The water level rises by 100cm3.

Principle of flotation says that a floating body displaces its own weight of fluid.

How do I relate mass, weight and volume in this scenario? I know I am missing something really basic here but in my head the volume of water that has been displaced is say, for the first example, 150cm3 LESS the volume of the object. So the weight of water displaced is less than the weight of the object as 1g of water = 1cm3?

Can someone explain how I am looking at this one back to front and missing the simple answer?

Thanks
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Avatar for Spandy
Spandy
3
Just conserve the forces.The force of gravity acting downwards will be balanced out by the weight of fluid displaced due to the submerged part of the body.
For example, in the first case, gravitational force=mass in kg*gravitational constant(10)
Thus, downward force is 1.5 Newton, and that's the weight of the fluid displaced.

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