No, hot air balloons float better than cold air balloons, so they weigh less (lighter than air), as one example.
Mass is not affected by temperature in any way.
The weight is the same, but the density is different.
With the exception of water when it turns to ice, a hot object has more volume than it does when it is cold.
same mass,greater dimensions ,,they go bouncy boing boing,because heat agitates the molecules therein,the breadth increases the weight/mass does not
I tried to find out, but I burned my hand in the process.
A number of people here are equating weight and mass.
These are not the same.
Mass is, roughly, the amount of 'stuff' something has, how hard it is to change somethings velocity.
Weight is the downward force of an object, caused by gravity and after mitigating factors (i.e. bouyancy)
It is not clear whether you meant weight or mass in the question, however an object is usually referred to as heavier if it weighs more, so I think it more likely you meant weight.
While a hotter object will have more energy, and thus due to mass-energy equivalence wll have more mass, a hotter object is also (usually) less dense. This lower density means that it takes up a larger volume, leading to a larger bouyant force and therefore reduced weight, despite the increased mass.
The effect of the reduced density is usually much larger than the increased energy, since the mass increase due to relativity is tiny. The equation, after all, is E = mc^2, so the mass increases with Ec^-2. Since c = 300000000 approx., this increase is incredibly small.
Ice is heavier per unit volume than water.
You would think that a cold object is more dense,
because the molecules are not moving as much.
When something is more dense, it weighs more
if volume is kept the same. However, I have heard
that water molecules form crystals and expand
when frozen, so that's an exception. But I think
most things are heavier when cold. It would be hard
to measure and prove with a solid object. If the solid object
was heated, it would expand in volume slightly. But you wouldn't
'trim' down to volume to make it the same volume
it used to be. You would think it just weighed the
same. To truly compare the weight of 2 objects,
their volume must be the same.
Depends on what we mean by the word "heavier" and what is causing the one object to have a higher temperature than the other. For macro-purposes, there is no practical difference. The mass equivalence of the added energy is tiny. For atomic scale or smaller, If that energy (heat, temperature rise) comes at the price of some internal conversion of mass, then there will be a reduction in "mass" but the total mass in terms of energy-equivalence of the substance will not alter except if there is emission of some of that energy to the outside (in which case the heating produces a loss of mass, so the hot object is less massive, and thus presumably less heavy).
If you add energy from the outside, then yes, the mass-energy equivalence requires that the "mass" (as energy equivalence) has increased. You have to add a lot of energy for it to matter except when dealing with very tiny masses or extremely precise measurements.