Question

calculate the total energy between 0s to 140s as shown in figure

Answer 1

i think energy can be calculated using
E=P×t
for ex. from 0 to 20 seconds..power is 10mW
i.e. E = 20×10 mJ= 200mJ
similarly you can add energy for all blocks
from 20 to 40 ,40 to 60 ,60 to 80, 80 to 100,100 to 140 ...
but remember.. time taken should be difference between blocks ...i.e. for 80 to 100 ..time should be 20 seconds..the difference..
hope it helped

Answer 2

Answer:(a) 0.944 mWh

Explanation: E= Pxt= Area

Given power in mW. But time in seconds. So

Convert time in seconds to hour (ie time in seconds/ 3600)

E=(1/3600)*[(10*20)+(30*20)+(20*50)+(20*20)+(40*30)]

=0.994mWh