Answer:
To solve this problem, we need to calculate the energy required to heat the water and then convert it to cost in PHP.
1. Energy Required to Heat Water:
- Mass of water: 8.5 kg
- Initial temperature: 18°C
- Final temperature: 43°C
- Specific heat capacity of water: 4180 J/kg K
Energy required to heat water = mass of water * specific heat capacity * temperature change
= 8.5 kg * 4180 J/kg K * (43°C - 18°C)
= 8.5 kg * 4180 J/kg K * 25 K
= 88,550 J
Convert energy from Joules to kilowatt-hours (kWh):
- 1 kWh = 3,600,000 J
- Energy required to heat water (in J) / 3,600,000 J/kWh
= 88,550 J / 3,600,000 J/kWh
≈ 0.0245 kWh
2. Cost to Heat Water:
- Cost per kWh: PHP 11.32
- Energy required to heat water (in kWh): 0.0245 kWh
- Cost to heat water = cost per kWh * energy required to heat water
= PHP 11.32/kWh * 0.0245 kWh
≈ PHP 0.278
Therefore, it costs approximately PHP 0.278 to heat 8.5 kg of water from 18°C to 43°C to fill a bath tub.