Question

Which of the following does not equal 1 kwh;? `a)3.6 *10^4` watt second `b)6 * 10^6` `c)1.34`Horsepower hour `d)80.43`Horsepower second

Answer 1

`"(a) and (d)"`

Explanation:

a)
`=> 3.6 × 10^4\ "W s"`

`=> 36 × 10^3\ "W s"`

`=> 36\ "kW s"`

`=> 36\ "kW" × cancel"s" × "3600 hr"/(cancel"s") color(white)(...)[∵ 1 = "3600 hr"/"1 s"]`

`=> color(red)(129600\ "kWh")`

`color(white)(...)——————————`

b)

`=> 6 × 10^6\ ?`

No units. Can’t say

`color(white)(...)——————————`

c)

`=> 1.34\ "Horse power hour"`

`=> 1.34 cancel"Horse power" × "745.7 Watt"/(1 cancel"Horse power")\ "hour"`

`=> 999.28\ "Watt hour"`

`=>\ color(blue)("Approximately 1 kWh")`

`color(white)(...)——————————`

d)
`=> 80.43\ "Horse power second"`

`=> 80.43 cancel"Horse power" × "745.7 Watt"/(1 cancel"Horse power") × cancel"s" × "1 hr"/(3600 cancel"s")`

`=> 16.66\ "Watt hour"`

`=>\ color(red)("0.0166 kWh")`