why a needle sinks in water while a wooden log floats?

Question

ans should be according to buoyant force

Answer 1

The density of iron/nickel in the needle is greater than water, while the density of wood is less (until that log becomes saturated with water). The weight of the water the needle displaced is less than the weight of the needle. The floating log weighs less than the water it displaced.

A ship does this because it is hollow, and the air volume makes up for the weight of the steel, so it displaces much more water volume than its volume. (a submarine is built to exactly displace its weight in water so it will sink, but remain close to neutrally buoyant when it is deep.

You can get a needle to 'float' on the surface of a still glass of water, but surface tension is holding it up, if you put soap in the water, it will break the surface tension and the needle will sink. (same prinicple water skimming insects use to ride on top of the water)...

Answer 2

a log has more surface area than a needle. if you try really carefully, you can get a needle to float on water.
Try filling a glass all the way to the top, so you get the "curve" and then put the needle on. It works!!

Answer 3

The needle sinks because it has a specific gravity of approximately 5.0 (equivalent to 41.5 pounds per gallon). Water has a specific gravity of 1 (equiv. to 8.33 pounds per gallon). The needle is much heavier so it sinks. Wood, in general is approx. 2.6 specl gravity and should sink also. But it is normally full of pore spaces that are full of air which makes it much lighter than air and therefore floats.

Answer 4

Paste the needle on top of the wooden log and now see it won't sink

Answer 5

A needle is denser than water; a log is less dense.

Answer 6

it is because of material of construction

Answer 7

the needle is denser than the log- duh!