In this post will will list examples of mechanical work and exercises with their solutions.
In physics it is called mechanical work to which it develops a force on an object, being able to influence its position or its amount of movement. That is, mechanical work is the amount of energy needed to set an object in motion , vary the characteristics of that displacement or even stop it.
Like other physical forms of work, it is usually represented by the letter W (from English Work ) and measured in joules, the unit for measuring energy. A July is equivalent to the work performed by a force of 1 Newton on a body that moves 1 meter in the exact direction and direction of the initial force .
Although force and displacement are vector magnitudes , in need of direction and sense, work is considered a scalar quantity , since it does not introduce variations in the direction and direction of the force that produces it.
In case the object is already in motion, the work will be carried out in the opposite direction to the trajectory of the displacement , managing to cancel or deviate the trajectory. In some cases this may require vector representations.
The first model is considered motor or positive work , the second work resistant or negative .
Then, in its simplest variant, the 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
- Push a table from one end of the room to another.
- Pull a plow as oxen do in the traditional field.
- Open a sliding window with constant force to the limit of your rail.
- Push a car that has run out of gas.
- Carry a bicycle by hand without climbing on it to pedal.
- Pull a door to enter a room.
- Tow a vehicle with another or with a crane that pull it and put it in motion.
- Drag someone’s arms or feet.
- Raise a piano with a system of ropes and pulleys in the air.
- Climbing a bucket full of water from the bottom of a well.
- Pick up a box full of books from the floor .
- Pull the load of the train , by the locomotive pulling forward.
- Knock down a wall by pulling it with a truck or high-powered truck.
- Pull a rope at the other end of which there are other people pulling it (cinchado).
- Hold a wall that comes down by applying its own weight.
- Hold a helium balloon that tends to rise at ground level.
- Win a beat overcoming the force that the opponent exerts in the opposite direction.
- Lift a weight off the ground , as Olympic athletes do.
- Pull a horse carriage , like those used in the past.
- Pulling a boat by an outboard motor , which makes it advance on the water.
Examples of mechanical work exercises
- A body of 198 kg is lowered down an incline, crossing 10 meters. What is the work done by the body?
Solution : Since the weight acts as force, the mechanical work formula is applied and it is obtained that: W = 198 Kg. 10 m = 1980 J
- How much force will an X body require to travel 3 meters doing a 24-joule job?
Solution : As W = F. d, we have that: 24 J = F. 3m
therefore: 24J / 3m = F
and: F = 8N
- How much work will it cost a person to push an iron box by 2 meters, applying a force of 50 N?
Solution : W = 50 N. 2m, then: W = 100 J