Answer:
<h2>1) there is no work done on the system</h2><h2>2) A) Using a lever to lift 100 newtons up to 4 meters on to a shelf</h2><h2 /><h2>3) P = 140 W</h2><h2>4) D) In a closed system, a system that isolated from its surrounds, the total energy of the system is conserved</h2>Explanation:
1) As we know that work done is the product of force and the displacement of the point of action where force is applied
So here we have
as there is no displacement in the direction where the force is applied
2)As we know that work is product of force and displacement
So we will have
So maximum work is done on
A) Using a lever to lift 100 newtons up to 4 meters on to a shelf
3)
As we know that power is rate of work done
so we have
4)
As per energy conservation we know that
D) In a closed system, a system that isolated from its surrounds, the total energy of the system is conserved