If a object is suspended in a jar (without touching the jar) filled with water will the wt. of jar increase?

Question

A jar is filled with water and is kept on an electronic weighing machine. Now a object tied with string is slowly lowered in the jar till it is completly immersed in water. The object however is not touching any of the walls or floor of the jar and is supported by the string. will the weight shown by the balance increase & why?

Answer 1

Warning: I think you have received some inaccurate information. Please be careful.

Here's what I believe the right answer is:

The weight registered on the scale will increase by an amount equal to the weight of the water that is displaced by the object.

Here's a way to think about it.
Imagine that you are holding the string and that the object is heavier than water, but only by a very small amount. When you lower it into the water, the water will provide some buoyancy, but not quite enough to float the object, But the water WILL support some of the weight, so the string (and your hand) will not be supporting the full weight of the object. and the weight that is being supported by the water rather than by the string is the amount by which the weight on the scale will increase.

Afternote: Now that I've seen Helmut's answer, I'll add the following:
If the jar is initially full, and if the object causes water to spill out of the jar (and off the scale so that it is not being weighed), then the reading on the scale WILL NOT CHANGE. The object has added weight to the scale equal to the water it displaced (as I said above). BUT, that same amount of water has been removed from the scale, so the net effect is that the reading on the scale is unchanged.

(Nonetheless, if this is a problem for science class, I think that my first answer is what they want you to answer. The version with the water spilling out is not well-defined. (Where does the water go? Does it drip onto the scale? Should you ignore it? I don't think they want you to guess about that. They want you to assume that the water stays in the jar (and just rises a little bit when the object is submerged in it).

Answer 2

No the string is supporting the weight of the object


Actuator is technically correct as to the the fact the water would support the weight of the object by buoyancy but the amount would be virtually unmeasurable on all but the most sensitive scales. The argument about the water displacement simply doesn't hold water pardon the pun!

You must assume the object is much more dense that the water to submerge and thus limits the buoyancy effect

Answer 3

Since you begin with a full jar, the jar will overflow by the volume of the object. If this water flows off the scale as well, the weight registered will decrease, as the object is supported independently of the scale.

BTW, an electronic scale is a spring scale, not a balance scale.

Answer 4

The weight of the object inside water is balanced by the tension in the string.

The weight that is pressing the machine is due to the container of water and water inside (which is less than the previous weighing).

Hence the machine shows less weight than the previous weighing.

I verified it .

Answer 5

in my opinion there will be a increase in weight because jar and object both are under the gravitaion and when the ball is dipped into water the buoyancy force will act upwards. and the ball will be displaces some amount of water. which will still remains in the jar.


so yes.


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Answer 6

No, because the string is taking (holding) the wieght of the object.
Otherwise, the object would fall in the jar.

Answer 7

yes the weight shown by balance will increase
the water will apply upward force on the object equal to weight of water displaced (archemidis principle) ,
and because of newtons third law (every action has equal and opposite rection) ,upward thrust is action ,whose reaction will be in downward direction which will add with the weight of water and weight shown by balance will increase
but the tention in string will reduce as the upward force applied by water will be subtracted from the weight of the object ,as they r in opposite direction

Answer 8

no, unless it is detatched from the string holding it up (that's whats taking its weight). in fact, water absorbed by the string would maek the scale go DOWN in weight o.0

Answer 9

sand, stones and water.... cease being bored with tips from procuring for a 'sixty seven camaro and driving it to my abode so i will keep it and shelter it like a sprint one...after which you will go away returned abode on a bus or something....

Answer 10

richie rich now thats a name i havent seen in a few years