In physics it is called mechanical work to the one that develops a force on an object, being able to affect its position or its amount of movement. Mechanical work is the amount of energy necessary to set an object in motion, vary the characteristics of said movement, or even stop it. For instance: when a table is pushed from one end of the room to the other.
What other physical forms of work, is usually represented by the letter W (from the English Work) and is commonly measured in joules, a unit for measuring energy. One joule is equivalent to the work done by a 1 Newton force on a body moving 1 meter in the direction and direction of the initial force.
Although force and displacement are vector quantities, endowed with sense and direction, work is a scalar quantity, it has no direction or sense (like what we call “energy”).
When the force applied to a body has the same direction and sense as its displacement, the work is said to be positive. On the contrary, if the force is applied in the opposite direction to the path of displacement, the work is called negative.
Mechanical work can be calculated according to the formula:
W (work in joules) = F (force in newtons). d (distance in meters).
Examples of mechanical work
- A table is pushed from one end of the room to the other.
- Oxen pull a plow in the traditional field.
- A sliding window opens with constant force to the limit of its rail.
- A car that has run out of gas is pushed.
- A bicycle is handy without climbing on it to pedal.
- A door is pulled to enter a room.
- A vehicle is towed with another or with a tow truck that pulls it and sets it in motion.
- Dragging someone by the arms or feet.
- A piano with a system of strings and pulleys rises through the air.
- A bucket full of water is raised from the bottom of a well.
- A box full of books is picked up from the floor.
- The cargo of the train is pulled, by the locomotive pulling forward.
- A wall is knocked down with a high-powered truck or truck.
- A rope is pulled and at the other end there are other people pulling it (cinched).
- A pulse is won by overcoming the force that the opponent exerts in the opposite direction.
- A weight is lifted off the ground, as Olympians do.
- A carriage is pulled by horses, like those used in ancient times.
- A boat is pulled by an outboard motor, which makes it advance over the water.
Examples of mechanical work exercises
- A 198 kg body is lowered down a slope, traveling 10 meters. What is the work done by the body?
Resolution: Given that the weight is a force, the formula of mechanical work is applied and it is obtained that: W = 198 Kg. 10 m = 1980 J
- How much force will a body X require to travel 3 meters doing 24 joules of work?
Resolution: As W = F. d, we have: 24 J = F. 3m
therefore: 24J / 3m = F
y: F = 8N
- How much work will it cost for a person to push an iron box by 2 meters, applying a force of 50 N?
Resolution: W = 50 N. 2m, then: W = 100 J