A steam iron draws 6.5 A when connected to a potential difference of 120 V.
(a) What is the power rating of this iron?
1 W
(b) How many joules of energy are produced in 20.0 min?
2 J
(c) How much does it cost to run the iron for 20.0 min at $0.014/kW·h?
$ 3
I got A and B i cant figure out C
P=I•U =6.5•120 =780 W,
E= P•t = 780•20•60 =9.36•10^5 J.
1J = 2.7•10^-7 kWh.
E = 0.26 kWh.
Cost = 0.26•0.014 =3.64•10^-3 $
the third answer is supposed to be in $
$3.64•10^-3 =$0.00364 =0.367 ¢
To find the power rating of the iron, we can use the formula:
Power (P) = Current (I) × Voltage (V)
Given that the iron draws a current of 6.5 A when connected to a potential difference of 120 V, we can calculate the power rating as follows:
P = 6.5 A × 120 V = 780 W
So, the power rating of the iron is 780 W.
To calculate the energy produced in 20.0 min, we can use the formula:
Energy (E) = Power (P) × Time (t)
Given that the time is 20.0 min (or 20.0 minutes), we need to convert it to hours since the power is given in watts:
20.0 min ÷ 60 min/hour = 0.3333 hours
Now, we can calculate the energy produced as follows:
E = 780 W × 0.3333 h = 260 J
Therefore, the energy produced in 20.0 min is 260 J.
To determine the cost of running the iron for 20.0 min at $0.014/kW·h, we need to calculate the energy used in kilowatt-hours (kW·h) and then multiply it by the cost per kilowatt-hour.
Since energy is given in joules, and 1 joule is equal to 0.0002778 kilowatt-hours, we can convert the energy produced in the previous question to kilowatt-hours:
260 J × 0.0002778 kW·h/J = 0.0722 kW·h
Now we can calculate the cost:
Cost = Energy (in kW·h) × Cost per kW·h
Cost = 0.0722 kW·h × $0.014/kW·h
Cost = $0.00101
Therefore, it would cost $0.00101 to run the iron for 20.0 min at $0.014/kW·h.