Question

an ice cream has a marked value of 700 kcal. how many kilo watt hour of energy will it deliver to the body as it is digested?

Answer 1

1 kWh = 1000 Watt × hour
= 1000 J/s × hour
= 1000 J/s × (3600 s)
= 36 × 10⁵ J

1 cal = 4.18 J
x = 36 × 10⁵ J

x = [(36 × 10⁵) / (4.18)] cal
x ≈ 86 × 10⁴ cal

So, we got 1 kWh = 86 × 10⁴ cal

Now,
700 × 10³ cal × 1 kWh / (86 × 10⁴ cal) = 0.814 kWh

∴ It delivers approximately 0.814 kWh of energy to body.