Question

show that 1kw=3.6 MJ.

Answer 1

One Watt (W) is 1 Joule per second, 1W=1J/s. So a kW=1000W=1000J/s. There are 60*60 seconds in an hour, so a Kilowatt hour is 
3600*1000 J=3.6*10^6 J. 
One mega-joule is 1 million Joules, 1MJ=10^6 J, so 
1 kWh=3.6 MJ.

Answer 2

To show that

1Kwh=3.6 MJ

Solution:

We know that

$1Kw=1000 w$

$1 hour=3600 s$

Substitute the values

Then, we get

$1Kw h=1000\times 3600$ J

$1Kwh=3600000J$

$10^5=100000$

$1Kwh=36\times 10^5J$

$1Kwh=\frac{36}{10}\times 10^6$

$1Kwh=3.6\times 10^6 J$

We know that

1MJ=$10^{6} J$

$1Kwh=3.6MJ$

Hence, proved.