posted by .

Jemima is sanding some floorboards with an electric sander which has a power rating of 360W. Jemima has the sander on for 45 minutes. The Sander is only 55% efficient. The electricity supplier charges 14.8p per kWh. What will be the cost of the 'wasted' energy?
I know how to work out the total cost but not the wasted energy cost...

  • Physics -

    Eff. = Po/Pi = 0.55
    360/Pi = 0.55
    Pi = 360/0.55 = 654.55 Watts = Power in

    Energy Wasted = 0.65455kW * (45/60)h =
    0.491 kWh.

    Multiply Energy wasted by the cost per kWh.

    I don't know what 14.8p mean.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics

    a high speed sander has a disk of 2.74 cm in radius that rotates its disks about the axis at a constant rate of 503 rev/min. determine the linear speed of a point 2.33 cm from the disk's center. answer in units of m/s
  2. phyical science

    A microwave oven has a power requirement of 1235 W. A frozen dinner requires 6.0 min to heat on full power. (a) How much electrical energy (in kWh) is used?
  3. Analytic Math( Grade 10)

    A contractor rented a sander for 5h and a polisher for $50. For another job, she rented the sander for 4h and the polisher for 8h. The rental fees for the job totalled $56. Find the hourly rate charged for each tool.
  4. math

    sander needs to find 73%of $239. what is a good estimate of the answer
  5. Math, I NEED HELP.c:

    A rental company charges a flat fee of x dollars for a floor sander rental plus y dollars per hour of the rental. One customer rents a floor sander for 4 hours and pays $63. Another customer rents a floor sander for 6 hours and pays …
  6. physics

    A high-speed sander has a disk 8.00 cm in radius that rotates about its axis at a constant rate of 1100 revolutions per minute. Determine the angular speed of the disk in radians per second.
  7. Physics

    HELP WITH c.!!! A electric bill showed 1200 kilowatt hours (kWh) purchased at a cost of $150.00. a. What does PECO charge per kWh?
  8. Math

    The amount of a monthly electric bill (B, measured in $) depends on the amount of electricity used that month (E, measured in kWh). A typical public utility charges $0.12 per kWh for the first 300 kWh used, $0.17 per kWh for the next …
  9. math

    In a normal month you use 1200 kWh of electricity. Your electricity provider has decided to increase the rate it charges for electricity by $0.05 per kWh. If you continue to use electricity at the same rate, how much more will it cost …
  10. maths

    jemima has twice as much money as matthew. jemima has four times as much money as sally. sally has $3 more than Andrew. If matthew has $14. how much money do Andrew, sally and jemima have?

More Similar Questions