A heater is used for 5 minutes to heat 500 g of water from 20˚C to 50˚C. What is the power of heater? Specific heat capacity of water is 4.2 J/gC.
Correct answer: C. 210 W
- A. 1260 W
- B. 12.6 kW
- C. 210 W
- D. 12.6 W
Explanation
To find : the power of the heater if the specific heat capacity of water is 4.2 J/g/C is..solution : first we should find the energy needed to heat the 500g of water from 20°C to 50°C.energy needed to raise the temperature of water, Q = msΔT= 500g × 4.2J/g/°C × (50°C - 20°C)= 500 × 4.2 × 30 J= 63000 Jnow the power of heater = energy dissipated by heater/time taken= 63000 J/5 min = 63000/300 = 210 Wtherefore the power of the heater is 210 Watt.As this is a numerical thus only one option is correct
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Power is the rate at which work is done or energy is transferred, with average power calculated over a time interval and instantaneous power found from P = Fv when force and velocity are aligned. Work includes units, mechanical efficiency, and the distinction between power and total work or energy.
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