1)how many joules of heat are required to melt 40 kg of ice at 0 C?

Question

2) how much current flows through a circiut if the resistance is 4 ohms and there is a 12-volt battery?
please show formula
3)how much current flows in a 12-watt radio connected to a 120-Volt circuit?
please show formula
4) if you have two 5-watt bulbs connected in a series and then in parallel.
which circuit arrangement will give you brighter bulbs?...i know its parallel can you explain why i dont understand?

Answer 1

1) Q = m*L
where Q is the quantity of Heat energy, m is the mass of ice and L is the latent heat of fusion
Q = 40kg*3.33x10^5J/kg

2) I = V/R where I is the current in ampere
V is the voltage in volt
R is the resistance in ohm
I = 12/4 = 3A

3) Power (P) = V*I
12W = 120V*I
I = 12/120
I = 0.1A

4) The parallel arrangement will give you more current and therefore more brighter bulbs.
Resistances or load resistance add up when connected in series and therefore the supply current is reduced but the total resistance in parallel is less than the the individual resistances and causes more current to flow, ergo brighter burning bulbs!

Answer 2

seem on your financial disaster approximately latent warmth. Q = m*L, the place Q is warmth required, m = mass of ice, and L = latent warmth of fusion. The latent warmth of fusion for water is 334 kJ/kg. So, Q = 40 kg * 334 kJ/kg = 13,360 kJ, or one million.336*10^7 J.

Answer 3

1) this is a question of specific heat capacity. lets change joules into kilojoules because you are working with kilograms. (you get the same result. the formula is 2.114 kj/40 kg* Deg C or about 84.6 kilojoules of energy, im not sure about the other three