is it possible to change a solid mass (i.e a block of steel) into pure energy?
913412
Not now.\nAlso, iron being at the nuclear energy low point, changing it to other elements takes power, rather than releasing it.
888632
to turn kg's into pounds you multlply the kg by 2.2
55228
Not always. If the object is in motion, then no. The total energy, aka total mechanical energy is always constant due to the Law of Conservation and Energy. It depends on the problem. Certainly,if you know the total mechanical energy in the system than you can find a variable for the kinetic energy or gravitational potential energy,assuming you given other variables.
9127
In nuclear reactions, MASS is converted into energy.
6409
Yes, bombard it with neutrons and it will release energy...\n\nWill it be efficient.. NO. but you can do so.
15241
Well yes and no. According the the principal of conservation of energy there is a set amount of energy and it can only be converted, not created or destroyed. But as we look into more complicated realms of physics, we understand that matter can be converted  into energy, and vice-versa.
832834
d)\notherwise some of work transforms to heat which is potential energy not kinetic.\nfor example when you kick the wall, acting forces are not elastic and do not rise kinetic energy of your feet or wall.
376938
Last I checked, alchemy was more of a psudo-science than an actual science that one could practice.  The changing of one form of energy to another (the entire basis of the theory of alchemy) is hardly difficult or unusual, however.  It's just a matter of an incredibly advanced knowledge of quantum mechanics.  Energy is constantly changing from one state of matter to another as atoms are gain/losing electrons, protons and neutrons into entirely different atoms.  As it is, the atoms in your a$$ are changing into atoms of your pants and vice-a-versa, the atoms in your pants are changing into the atoms in your chair and vice-a-versa, the atoms in your chair are changing into the atoms of the floor and vice-a-versa, and so on and so on.  In order for alchemy to work, you would need to know how to manipulate the atoms of one element to resemble the atoms of your desired element.  Unfortunately, you can't just pick up atom kits from the store to build your own custom elements. :S
530744
An alternative energy source
189204
It is converted into a different state of mass (i.e.-liquid, gas, solid), however, the mass of the converted form is equal to the mass of the original form.
761342
We did something like this in my physics lab with an Atwood machine.  It was a pully with weights hanging from it.  I can't exactly remember how it worked, but maybe this will inspire you.  We also did something with an air track and these two masses colliding and we'd see which one would go in which diretcion.  You need a nearly frictionless surface, like an air hockey table or ice slab.
37744
you can't convert heat energy directly into free energy (electric current).  That would violate the second law of thermodynamics.  you can use a temperature DIFFERENCE to harvest free energy from thermal energy...
102002
Sure, but as you can tell, it would take a whole lot of energy to make a little mass.  Just think atom bomb.
523994
Once carbon is turned into a diamond (which takes a VERY long time), it cannot be changed back. Well, it could, but the energy required is enormous.  Remember, diamonds are one of the hardest substances on the planet.
420623
You can't. Alchemy is a myth. Without nuclear reactions, you can't turn lead into gold, or any element into any other element.
979053
Mass is always mass in any situation. You can´t change the mass, you only can change some properties of the mass, such as, weight (according the gravity), quantity of cinetic energy (accordind the velocity of the mass), etc. But the mass is always the same mass!!!
933767
As I understand it a trebuchet is a giant catapult, yes?\nSo all the potential energy is contained within the springs, or twisted ropes or rubber bands or whatever holds the arm down.\nThis sounds to complicated without more info.\n You could get an approx answer by measuring the kinetic energy of the stone when it is released + the kinetic energy of the Trebuchet when it rolls back wards + the energy converted to heat by friction. The total will be the potential energy.