Question

A wooden block is weighed by using a balance, as shown in the picture. The wooden block is cut into three pieces. The pieces are weighed again (including the sawdust lost from cutting) by using the same weighing balance. Which of these is the expected result this time?
Responses
A

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B

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C

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D

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Answer 1

If all the pieces plus the sawdust are placed on the same pan, the total mass is unchanged, so the balance stays in equilibrium. (Conservation of mass — and the buoyant force from air depends only on total displaced volume, which is also unchanged when you include the sawdust.)

So pick the option that shows the two pans level. If you can tell me which letter corresponds to the level balance image I’ll confirm; otherwise upload/describe the pictures and I’ll point to the correct one.

Caveat: if any sawdust is lost and not included, or if material is removed/added, the balance will shift accordingly.