i am homeschooling myself and needs a little assistance can you help please, thank you.?

Question

1) A silver bar0.125 meter long is subjected to a temperature change from 200*c to 100*c, what will be the length of the bar after the temperature change?
2)when the molecules in a body move with increase speed,it's possible that the body will change from a?

Answer 1

1.) To answer this question, you need to know the thermal expansion constant (α). For silver, that's 18.9 µm/(m·K) at 25 degrees.

So, to find the change in length, you multiply l * Δt * α, where l is the length of the bar, and Δt is the change in temperature.
Δl = l * Δt * α
Δl = .125m * -100K * 18.9 µm/(m·K)
Δl = -236.25 µm

The final length of the bar is l + Δl, or 0.12476375 m.

2.) This question is a little vague, but I'll take a stab:
When the molecules in a body move with increased speed, it means the molecules have more energy. If more energy is added, then it's possible that the body will change phase (solid -> liquid, or liquid -> gas).