Junior high school physics: energy conversion, about internal energy Please give examples of the life in which internal energy is converted into other forms of energy and other forms of energy are converted into internal energy In addition, when baking bread in an electric oven, is it right that electric energy is converted into internal energy? Generally speaking, most of the internal energy is converted into other energy by gas or liquid? In addition, can the energy of solid be converted into internal energy by other energy? Isn't its molecular structure very stable?

Junior high school physics: energy conversion, about internal energy Please give examples of the life in which internal energy is converted into other forms of energy and other forms of energy are converted into internal energy In addition, when baking bread in an electric oven, is it right that electric energy is converted into internal energy? Generally speaking, most of the internal energy is converted into other energy by gas or liquid? In addition, can the energy of solid be converted into internal energy by other energy? Isn't its molecular structure very stable?

(1) Internal energy is converted into mechanical energy: the human body does external work, such as riding a bicycle;
Other forms are transformed into internal energy: if you rub your hands constantly, your hands will get hot
(2) When baking bread: electric energy is converted into internal energy
(3) There are solids, but it's not easy
(4) Solid can be transformed, and its molecular structure is very stable, so transformation requires more other forms of energy

A paddy field covers an area of 2400 square meters. It needs to irrigate water with an average depth of 0.1 meters, regardless of the loss of water infiltration. (1) if the water is pumped from a canal 2m deep away from the paddy field by a pump, at least how much work should the pump do? (2) if the power of the pump is 2.4kw, how long does it take for the pump to pump the water

(1) M water = V water ρ water = HS ρ water
=Cubic kilogram per cubic meter of 0.1M * 2400m2 * 1 * 10
=The quintic kilogram of 2.4 * 10
w=mgh
The quintic power of 2.4 * 10 kg * 9.8 N / kg * 2m
=4704000 coke
（2）2.4kw=2400w
t=w/p
=4704000j / 2400W
=1960s

The power is supplied to a lamp marked "PZ & nbsp; 220-60" in a distant construction site by a power supply of 220 v. due to the resistance of the wire, the actual power consumed by the bulb is 55 W. then the power consumed by the wire ()
A. Less than 5wb. Equal to 5wc. Greater than 5wd. Uncertain

If the wire resistance is ignored, that is, the voltage of 220 V is all connected to the bulb of "PZ & nbsp; 220-60", the bulb will light normally, and the power is 60 W; if the wire resistance is not ignored, that is, the resistance in the circuit will increase, and the total power consumed by the circuit will decrease, that is, less than 60 W, while the actual power of the bulb is 55 W, so the power on the wire can only be less than 5 W; therefore, select a