Http://tomschoderbekchem.blogspot.com/2014/09/nuclear-fission-and-fusion-worksheet.html
73 Newton is the correct answer
Given :
Mass of block , M = 20 kg .
Force applied , F = 80 N .
Acceleration of block ,
.
To Find :
The coefficient is Kinetic force friction between the block and the table .
Solution :
We know , Force equation on block is given by :

Therefore , coefficient is Kinetic force friction between the block and the table is 0.15 .
Hence , this is the required solution .
Answer:
false. it's positive terminal of an electric cell