We are given the task of heating a beaker of water using only mechanical energy. What are some ways that this could be done using simple materials?
The mechanical energy can be converted to any other form of energy.
Use a generator to power a heating element.
You could cool the water by the chilly reception you’ll get by asking people to do your homework on a message board dedicated to fighting ignorance.
If you take a pool pump (or almost any pump), and connect the inlet right to the output via a short hose and somehow get water into this ‘loop’. Run the pump for a bit and the water will heat up.
How hot do you want the water to get?
Stirring it, or pouring it onto the floor would get you some heat.
For higher temps, consider an underwater variation on the Bow Drill.
Rub two sticks together to make a fire.
My Vita-Mix will boil water in about 5 minutes from the friction of the blades. Is a Vita-Mix a “simple material”? Prob’ly not.
How about converting the mechanical energy to heat?
Or doing your own homework?! 
You could also use a generator hooked up to a hot plate.
Turning shaft is mechanical energy, which you convert to electrical energy to heat.
Think friction.
NurseCarmen, I am 42 years old and this is hardly my homework. Never assume.
Why did you start the post “We are given the task?”
I know you are new to the boards, so let me explain my reply. Quite often, kids come in and ask questions that have clearly come from school assignments. Some have even had the balls to put multiple questions in a single thread. Yours certainly looked the part. A question, no input, no ideas of your own.
We thought of this but rejected the idea because even though the rubbing is mechanical, the energy from the burning fuel is chemical. In the same way, the idea of lighting a match is not a valid solution because only a fraction of the energy produced is mechanical.
I understand your concern. It would be great to be able to get all the materials together and test my predictions experimentally. Unforturnately, I am more of a thinker than a doer. I did think of friction and heat from a generator. I was wondering if I was missing something obvious.
I love this board because it is a fast way for me to pick the brains of many many people.
For my part, I would be impressed if any of my students had the ambition to even ask for my advice on a topic such as this let alone go online to look for an answer.
I may be a new member but I have been reading the message board for over a year. I am familiar with how it works. All kinds of questions get asked. I love the message board because I can learn from so many people.
In the future, I will phrase my questions in such a way as to not look like a student.
Get two steel plates. Place the water on one and spin the other underneath and touching the first plate (obviously the top plate would need to be anchored from moving). The friction will heat things nicely (think of the brakes on your car). You can spin the plate with any number of methods but getting things hot enough to boil water wouldn’t be too hard and the whole setup can be purely mechanical.
(Note maybe two “steel” plates are not the best material choices but whatever would be ideal the premise is the same)
Here is a simpler version of what I was talking about. 100% mechanical (human powered by hand).
Better yet, use a centrifugal pump and dead head it.
If ‘mechanical energy’ isn’t limited to kinetic energy (and I don’t think it is), then I’d just set the beaker of water out in the sun.
Setting the beaker in the sun? The water isn’t being heated by mechanical energy, but by radiation.
You picking the beaker up and carrying it outside is certainly a contributing factor.
The real question is, how could you not heat up the water? The thing about heat is, it’s really easy to convert any form of energy to heat (far easier than the reverse). Any way you could possibly introduce mechanical energy to the system, you’re almost guaranteed to convert almost all of it to heat.