Number 29 plz help physics

a. E = 900000 J = 900 KJ

b. ΔT = 8.18 °C

c. Cost = $ 7.2  

Explanation:

a.

The energy can be given by:

where,

E = Energy = ?

P = Power = 500 W

t = time = (0.5 h)(3600 s/1 h) = 1800 s

Therefore,

E = 900000 J = 900 KJ

b.

The change in temperature of room air is given by the following formula:

  (since 50% of energy is used to heat air)

where,

m = mass of air = 50 kg

C = specific heat of air = 1.1 KJ/kg.°C

ΔT = Change in temperature of air = ?

Therefore,

ΔT = 8.18 °C

c.

First, we will calculate the total energy consumed:

Now, for the cost:

Cost = $ 7.2