Question

Integrated Concepts A lightning bolt strikes a tree, moving 20.0 C of charge through a potential difference of 1.00×102 MV . (a) What energy was dissipated? (b) What mass of water could be raised from 15ºC to the boiling point and then boiled by this energy? (c) Discuss the damage that could be caused to the tree by the expansion of the boiling steam.

Answer 1

Answer:

a) 2*10^9 J

b) 764.8 kg

Explanation:

Given that

Energy of charge, q = 20 C

Potential difference, ΔV = 1*10^2 MV = 1*10^2 * 10^6 V = 1*10^8 V

a)

To find the energy dissipated, we use the formula

ΔU = qΔV

ΔU = 20 * 1*10^8

ΔU = 2*10^9 J

b)

Change in temperature, ΔT = 100 - 15°

ΔT = 85° C

Change in energy, ΔU = 2*10^9 J

Specific heat of water, C = 4180 j./Kg.K

Latent heat of vaporization, L(v) = 2.26*10^6 J/Kg

Q1 = mcΔT

Q2 = mL(v)

Net energy needed, U = Q1 + Q2

U = mcΔT + mL(v)

U = m (cΔT + L(v))

m = U /[cΔT + L(v)]

Being that we have all the values, we then substitute

m = 2*10^9 / [(4180 * 85) + 2.26*10^6]

m = 2*10^9 / (3.553*10^5 + 2.26*10^6]

m = 2*10^9 / 2.615*10^6

m = 764.8 kg

c)

Having 765 kg of steam at the temperature would have extreme effect on the tree, damaging it permanently. Possibly even blowing it to pieces