Answer:
a) cost = $ 0.29
, b) cost = $ 0.046
, c) cost = $ 2.80
Explanation:
a) Let's find the energy consumed by this bulb, which is the product of the power and time
energy = P t
energy = 100 24 = 2400 W h
as the cost of energy is given in kWh we reduce this value
Energy = 2400 Wh (1 kW / 1000W)
Energy = 2.40 kWh
Calculate the cost of energy
cost = 0.12 2.40
cost = $ 0.288
cost = $ 0.29
b) energy = 16.0 24 = 384 Wh
we reduce to kWh
energy = 0.384 kWh
cost = 0.12 0.384
cost = $ 0.0461
cost = $ 0.046
c) let's find the power consumed by the oven
P = I V
P = 20.0 220
P = 4400 W
we look for the energy consumed
energy = 4400 5.30
energy = 23320 Wh
we reduce to kWh
energy = 23.32 kWh
we calculate the cost of this energy
cost = 0.12 23.32
cost = $ 2,798
cost = $ 2.80
You can figure this out using the equation for specific heat: q=mcΔT; where q is the heat, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature (in °C or K).
In this case we're solving for q, given m = 20000 g, c = 4.18 j/g°C, and ΔT = 35°-0°=35°. This means q = 20000 x 4.18 x 35 = 2 926 000 J, or 2926 kJ.
We should really talk about the energy of a photon.
Photon Energy= h x c/ wavelength
where h is Planck's constant and c is the speed of light
h = 6.63 x 10^-34
c =3x 10^8
Energy = 2.37 x 10^-21
Start with 2,000 grams.
After 1 half-life, 1,000 grams are left.
After another half-life, 500 are left.
After another half-life, 250 are left.
After another half-life, 125 are left.
That was FOUR half-lifes.
X = 4 .