Democritus was a Greek philosopher who lived between 470-380 B.C. He developed the concept of the 'atom', Greek for 'indivisible'. Democritus believed that everything in the universe was made up of atoms, which were microscopic and indestructible. Democritus had many remarkable insights for his time.
Answer:
Depending on the locomotive, it can use steam, batteries or a diesel engine.
A car uses a DC battery to start it and an internal combustion engine to run it (unless it is an electric car, then it uses DC batteries.
A portable media player can use either a/c or a battery.
A flashlight uses DC batteries.
Answer:
Part a)

Part b)

Explanation:
Part a)
As we know that initially the two blocks are connected by a spring and initially stretched by some amount
Since the two blocks are at rest initially so its initial momentum is zero
since there is no external force on this system so final momentum is also zero

now for initial position the speed is zero

now we have

Part b)
now for ratio of kinetic energy we know that the relation between kinetic energy and momentum is given as

now for the ratio of energy we have

since we know that momentum of two blocks are equal in magnitude so we have
now we have

Answer:
A. Air
Explanation:
A thermal insulator is a material that does not let the heat trasmitting through it, or it transmits heat not very efficiently.
Generally, the lower the density of the material, the better insulator the material is: this is because in materials with very low density, particles are very spread apart, so they cannot collide with each other, and so the vibrations of the particles (which determine how hot a substance is) cannot be transmitted very efficiently.
In the options listed in this problem, air is the material with lowest density, therefore it is the best thermal insulator among them.
The component that could Chang leave out and still light up the bulb is the switch.