Energy needed to keep a 75w bulb burning for 1 hour = 270kj Calculate energy neede to keep it burning for 3 hours?
In J and kcal?
I got the J: It is 270kj x 1000/1 x 3/1 = 810000=8.1 x 10^5J
But How Do I get the kcal?
Thank you
To convert the energy in joules (J) to kilocalories (kcal), you can use the conversion factor: 1 kcal = 4184 J.
To calculate the energy needed to keep the 75W bulb burning for 3 hours in kcal, you can follow these steps:
1. Calculate the energy needed for 3 hours in joules:
Energy (J) = Power (W) x Time (h)
Energy (J) = 75 W x 3 h = 225 Wh
2. Convert from watt-hours (Wh) to kilojoules (kJ):
Energy (kJ) = Energy (Wh) x 1000 / 1
Energy (kJ) = 225 Wh x 1000 / 1 = 225,000 J
3. Convert from joules (J) to kilocalories (kcal):
Energy (kcal) = Energy (J) / 4184
Energy (kcal) = 225,000 J / 4184 ≈ 53.77 kcal
Therefore, the energy needed to keep the 75W bulb burning for 3 hours is approximately 8.1 x 10^5 J or 53.77 kcal.
1 cal = 4.184 J
1000 cal = 1 kcal.