Question

A waiter is carrying a tray above his head and walking at a constant velocity. If he applies a force of 5.0 newtons on the tray and covers a distance of 10.0 meters, how much is the work being done?
0 joules
2 joules
-2 joules
50 joules
-50 joules

please help me

Answer 1

Answer:

0 joules is the work being done.

Explanation:

Work is defined as the force that is applied on a body to move it from one point to another. When a force is applied, an energy transfer occurs. Then it can be said that work is energy in motion.

When a net force is applied to the body or a system and this produces displacement, then that force is said to perform mechanical work. This work can be positive if the system gains energy or negative if the system loses energy.

In the International System of Units, work is measured in Joule. Joule is equivalent to Newton per meter.

The work is equal to the product of the force by the distance and by the cosine of the angle that exists between the direction of the force and the direction that travels the point or the object that moves.  

In this case, the angle between the force and the displacement is 90 degrees. This is because the normal force in the tray, that is to say a force vertically upwards. And the displacement is in the horizontal direction. Then the cosine of 90 degrees will have a value of zero. So when performing the multiplication between force, distance and the cosine of the angle that exists between the direction of the force and the direction that travels the point or the object that moves, the work will have a value of zero.

This means that no work is done.

Answer 2

In physical terms, a force does work if it moves an object in the direction the force is pointing towards.

In your example, the force is pushing a tray up. But the force doesn't move the tray any further up. It remains at the same height. 

The is no force done by this force.