Calculating Thermal Energy Supplied by Heater in 30.0s - Kilo-joules

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To calculate the thermal energy supplied by a heater with a resistance of 15.0 W operating at 120.0 V over 30 seconds, Ohm's Law and energy formulas are applied. The power is determined using the formula Power (W) = Voltage (V) / Resistance (R), resulting in a power output of 8.0 A. The energy transfer is then calculated using Energy (J) = Power (W) x Time (s), yielding 450 J or 0.45 kJ. This confirms that the heater supplies 0.45 kJ of thermal energy in 30 seconds. The calculations illustrate the relationship between voltage, resistance, and energy output in heating applications.
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A heater has a resistance of 15.0 W. It operates on 120.0 V. What thermal energy is supplied by the heater in 30.0 seconds? Answer must be in Kilo-joules.


Well o_o ..it would be nice if you could try to help me with this question. Since I recently moved from Germany to the U.S. with my parents.. and we weren't at this point in my old school.
 
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Do you mean 15 Ohms resistance?

Use Ohm's Law to calculate the power usage (voltage times current) and note that energy = power times time.
 
questionmaster said:
A heater has a resistance of 15.0 W. It operates on 120.0 V. What thermal energy is supplied by the heater in 30.0 seconds? Answer must be in Kilo-joules.

Voltage (volts) = Current (amps) x Resistance (ohms)
Power (watts) = Voltage (volts) x Current (amps)

Therefore:
Resistance (ohms) = Power (watts)

Energy Transfer (J) = Power (W) x Time (s) => E = 15 x 30
=> Answer should be 450 J or 0.45 kJ.

The Bob (2004 ©)
 

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