The coefficient of expansion is 13 * 10^-6 m per meter length.per oK
The temperature difference = 42 - - 8 = 50 oC
delta T = (42 + 273) - (-8 + 273) = 50 oK
delta L = L * 13* 10^6 m/oK
oK = 50 oK delta L = 19.5 cm = 19.5 cm [1m / 100 cm] = 0.195m
So we need to find the length and it is computed by:
0.195= L * 13 * 10^-6 * 50 L = 0.195 / (13*10^-6*50) L = 300 m
What? Do you have a picture of the problem ?
Static electricity is electricity produced locally that does not flow. It is produced by electrons being rubbed off one object and collecting on another. It cannot flow through a wire like the electricity in your home.
Example:
1) Rub a balloon on your hair and it will stick to the wall. The balloon rubs electrons off your hair and picks up a negative charge. Your hair, in turn, is left with a positive charge. You may even notice your hair has "static" and is standing out from your head.
2) Comb your hair with a plastic comb then use it to pick up small pieces of paper. The comb picks up electrons from your hair and becomes negatively charged. It uses this charge to attract the pieces of paper.
3) Rub your slippered feet on the carpet and then touch something metal like a door knob. The "shock" you feel is static electricity. You pick up electrons from the carpet and discharge them on to the door knob.
