Marie lifts a 5 kg mass from the floor and puts in on a table one metre high. What is the work done?

The work done was 49.05 N*m.

Explanation:

The work done by a a force is given by:

We first need to calculate the force necessary to lift the box from the ground, the force needed for is the weigh of the box, which is shown below:

Therefore the work done by lifting the box and placing it on the table is:

The work done was 49.05 N*m.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.