Question

Anyone can help me with these questions:
1. BC Hydro charges $5.91 per kWh. How long does it take a 100 W light bulb to use up $1.00 of energy? (answer = 1.7h)
2. A small bag of chips contains 230 Calories (1000 calories = 1 calorie = 4.19 kJ). To what max. height could a 70 kg person climb with this amount of energy?

Thanks :)

Answer 1

P=100 W =0.1 kW
0.1•t kWh → $1
1 kWh → $5.91
t=1/0.1•5.91 =1.7 h
2.
1000 calories = 1 kilocalorie = 4.19 kJ
mgH=70•9.8•H = 230 C = 963 J
H= 963/70•9.8 =1.4 m