The total amount of energy remains constant in an isolated system. It implies that energy can neither be created nor destroyed, but can be change from one form to another.
Answer:
Multiply the air pressure by the area of the tabletop.
Explanation:
The relationship between pressure, force and area is given by:

where in this case, p is the air pressure, F is the force exerted and A the area of the tabletop. By re-arranging the equation, we can solve for F, the force exerted:

So, the correct answer is:
The force exerted on the tabletop can be found by multiplying the air pressure by the area of the tabletop.
Answer:
Explanation:
Caty , Use the relativity formula for length. ( they teach this in H.S. ? ) it's from my Modern Physics in college, A 300 level class
L = 

L = 3 
L = 0.9367496998 meters
L = 0.94 meters approx
That will depend on the coefficient of friction between the sliding surfaces, and also on Zak's weight. We don't have any of that information.
125 W is the power output of this machine.
Answer:
Explanation:
Power is defined as the amount of work done on the system to move that system from its original state within the given time interval. So it can be determined by the ratio of work done with time interval. As work done is the measure of force required to move a system to a certain distance. Work done is calculated as product of force with displacement.
So in the present case, the force is given as 100 N, the displacement is given as 5 m and the time is given as 4 s, then power is

As Work done = Force acting on the machine × Displacement
So 
Power =
=125 W
So, 125 W is the power output of this machine.