A heater dissipates 1400 W of power when it is connected to a 140 V battery. Par

Question

A heater dissipates 1400 W  of power when it is connected to a 140 V  battery.

Part A

What current will flow through the heater when it is connected to the battery? answer should includes I=____ A

Part B

What is R, the resistance of the heater? answershould include R=___ OHM

Part C

How long does it take to raise the temperature of the air in a good-sized living room that is 4.00 m  × 8.00 m × 7.00 m by 10.0C? Note that the specific heat of air is 1006 J/(kgC) and the density of air is 1.20kg/m3. Answer should include DELTA t=___ MINUTES

Explanation / Answer

A) use, P = V*I

==> I = P/V

= 1400/140

= 10 A

B) use Ohm's law,

V = I*R

==> R = V/I

= 140/10

= 14 volts

C) energy supplied by the heater = Heat obsorbed by the air

P*dt = m*C*dT

dt = rho*V*C*dT/P

= 1.2*4*8*7*1006*10/1400

= 1931 s

= 1931/60

= 32.2 minutes

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