Question

express 5 kWh into joule

Answer 1

kWh means kilowatt-hour,
1 kilo watt=1000 watt
1 hour=3600 sec
and
1 watt second = 1 Joule
so
5 kWh = 5×1000×3600 =18000000 Joule

Answer 2

Given: Energy = 5 kWh

To Find: Energy into joule, E.

Solution:

To calculate E, the concept used:

• Energy consumed by electrical appliances is called electrical energy.

• It can be expressed in joules and kWh.

• 1 kWh is the commercial unit of electricity. It is the electrical energy consumed by an electric appliance of power 1 kilowatt, for one hour.
• The amount of energy consumed by an electric appliance of power 1 watt, used for 1 sec., is called 1 joule.

Applying the above concept:

First, convert 1 kWh into 1 J:

1 kilowatt = 1000 watt

1 kW = 1000 W

and, 1 hr = (60 x60) sec

              = 3600 seconds

∴ 1 kWh = (1000 x 3600) J

             = 1000 x 3600

             = 36 x 100000

             = 36,00000 J

1 kWh    = 3.6 x 10⁶ J

In 5 kWh, joules are:

5 kWh   = 5 x 3.6 x 10⁶ J

             = 5 x 3.6 x 10⁶

             = 18.0 x 10⁶

5 kWh  = 1.8 x 10⁷ J

          E  = 1.8 x 10⁷ J

Hence 5 kWh has 1.8 x 10⁷ joules.