The work done by the elephant to lift one log is the force multiplied by the height at which the log has been lifted:

And so, the total work done to lift the 7 logs is 7 times the work done to lift each log:
Answer:
Unbalanced forces is the correct answer.
Explanation:
Matter can be many things, but is mostly made of atoms. Atoms are small things that cannot be seen directly, as lights either passes through it or alters it. However, we know that atoms are made of 3 parts, those being the proton, neutron, and electron.
Protons have a positive electromagnetic charge.
Neutrons have no charge.
Electrons have a negative charge equal to the protons positive charge.
Protons and neutrons make up what's called the nucleus, which is orbited by the electrons.
Protons and neutrons also share another thing in common, that being their composition.
Until relatively recently, we thought that these were the smallest particles in the universe, and indestructible. However, modern discoveries have revealed that they are actually made of quarks and gluons.
These are actually indestructible, being part of the group that is elementary particles.
Mercury is very harmful to the average human being. the mercury can easily be released from the lamp if the lamp is knocked over and broken. mercury is also harmful if inhaled. sodium on the other hand is not harmful in any way.