Which is heavier: a kilogram of feathers or a kilogram of lead?

If you asked a scientist you might get a different answer than if you asked a layman. Let's compare a kilogram of lead with a kilogram of aluminum. You likely would use the same scale to measure both samples. But, the aluminum is much lighter and would take up far more space than the lead. The samples would displace different amounts of air and the buoyancy of air would affect the scale readings by a small amount. Therefore to obtain accurate measurements you must weigh the samples in a vacuum or calculate the buoyancy and compensate the weight measurements. If this is true for lead and aluminum it is even more true for lead and feathers (or even lead and butter). Chemists often do have to compensate for air buoyancy when measuring chemicals so that when they react none are left over.

Assuming that by 'heavier' you mean 'which weighs more' then the two weight the same. 1 kilogram is a mass. Weight is mass times the accelleration due to gravity, which on earth is about 9.8 meters per second squared. Thus both the feathers/butter and the lead weigh about 9.8 newtons or 2.2 pounds. They will however, most likely fall at different rates due to differences in air resistance. Feathers fall very slowly because their large surface area generates an incredibly large air resistance per weight, whereas a ball of lead has a relatively low surface area and thus a low wind resistance.

I would find a place in Central Park, maybe near that big gold statue, and put up a big stage. On the stage I'd have a large set of scales. One side would have a kilogram of butter, the other a kilogram of lead. They would balance perfectly as a they both weigh the same - a kilogram.

No mere simple demonstration would do. I say "Go big or stay home!!"

Since weight, a force, is equal to mass * acceleration, and the acceleration on the surface of the earth is always around 9.8m/s^2, both will weight the same since it's the same mass. Unfortunately, it's not easily demonstrated since feathers can be picked up by the wind. In a vacuum, you would be able to see any 2 objects fall at exactly the same speed.

Actually, one thing you could do is put a bag of feathers and a bag of lead onto a scale and both will weigh the same if they are both 1 kg and would be unaffected by the wind.

It is possible to demonstrate in Central Park (or anywhere else) using a very simple balance scale. Place the feathers and the lead (or the butter?) the same distance from the fulcrum and they would balance perfectly.

This is not necessarily to say that they weigh the same (although they do in this experiment). A kilogram is not a measure of weight, but of mass. A kilo is unchanging, no matter the gravity field. Thus, if you took your kilo of lead and kilo of feathers to the moon, they would WEIGH one sixth as much, but would MASS the same ... One Kilo!

Cheers.

Obviously they are both the same weight and mass however the feathers are much less dense. To demontrate this to my freinds in central park, I would cram the feathers into a small box and put the lead into a box of the same size and ask about a dozen people to try to guess which one is heavier on average the people will say they are the same weight.

Neither. They both weigh a kilo.

If I had to demonstrate in the middle of Central Park, I would drag a scale, a kilogram of butter, and a kilogram of lead out there, then weigh the lead and butter separately.

a kilogram is a measure of weight. the denser the matter, the less is needed to weigh a kilogram, the llghter the weight of the matter, the more is needed to weigh the same. because a certain weight is the same. some you just have to use more or less depending on its density. for example, i weigh about 255lbs,now take a football player weighing the same, because his weight is mostly muscle, it actully takes up less space than my 255lbs of fat,which is much less denser and require more space. so weight is weight. you must add in the density of it to find out which takes the more or less of what you are weghing. so whether it's lead compared to feathers or butter, it's the density of one versus the other.

there won't be any heavier or lighter because you said "a kilogram" of feathers and "a kilogram" of lead. when both have the same weight, 1 kilogram, how can there be one heavier than the other??

if you had said 1 feather and 1 lead , then the lead would have been heavier and in your question they are of the same weight.so nothing to demonstrate.

To demonstrate......kilogram of butter and a kilogram of lead on scale.

Result: both weigh the same although there were be more butter than lead since the density of the lead is higher than butter.

Although kilogram is a mass, not a weight, they do both have the same mass, 1 kilogram. Because of this, they have to weigh the same, which would be 9.8 Newtons. (1 kg * 9.8m/s^2)