Definition of Work in Physics

Definition of Work in Physics In  physics, work is defined as a  force  causing the movement- or displacement- of an object. In the case of a constant force, work is the scalar product of the force acting on an object and the displacement caused by that force. Though both force and displacement are vector quantities, work has no direction due to the nature of a scalar product (or dot product) in vector mathematics. This definition is consistent with the proper definition because a constant force integrates to merely the product of the force and distance. Read on to learn some real-life examples of work as well as how to calculate the amount of work being performed. Examples of Work There are many examples of work in everyday life.  The Physics Classroom  notes a few: a horse pulling a plow through the field; a father pushing a grocery cart down the aisle of a grocery store; a student lifting a backpack full of books upon her shoulder; a weightlifter lifting a barbell above his head; and an Olympian launching the shot-put. In general, for work to occur, a  force has to be exerted on an object causing it to move. So, a frustrated person pushing against a wall, only to exhaust himself, is not doing any work because the wall does not move. But, a book falling off a table and hitting the ground would be considered work, at least in terms of physics, because a force (gravity) acts on the book causing it to be displaced in a downward direction. Whats Not Work Interestingly, a waiter carrying a tray high above his head, supported by one arm, as he walks at a steady pace across a room, might think hes working hard. (He might even be perspiring.) But, by definition, he is not doing  any  work. True, the waiter is using force to push the tray above his head, and also true, the tray is moving across the room as the waiter walks. But, the force- the waiters lifting of the tray- does not cause the tray to move. To cause a displacement, there must be a component of force in the direction of the displacement, notes The Physics Classroom. Calculating Work The basic calculation of work is actually quite simple: W Fd Here, W stands for work, F is the force, and d represents displacement (or the distance the object travels).  Physics for Kids  gives this example problem: A baseball player throws a ball with a force of 10 Newtons. The ball travels 20 meters. What is the total work? To solve it, you first need to know that a Newton is  defined as the force necessary to provide a mass of 1  kilogram (2.2 pounds)  with an acceleration of 1  meter (1.1 yards) per second. A Newton  is generally abbreviated as N. So, use the formula: W Fd Thus: W 10 N * 20 meters (where the symbol * represents times) So: Work 200 joules A  joule,  a term used in physics, is equal to the  kinetic energy  of 1 kilogram moving  at 1 meter per second.

Spanish Phrases Meaning Unless

Spanish Phrases Meaning Unless A menos que and a no ser que are two of the most common ways in Spanish to express the idea behind the English conjunction unless. Because the verb following either one of these phrases refers to something that hasnt happened yet and may never happen, it typically is in the subjunctive mood. In a sense, these phrases are used in making negative conditions, or the opposite of si or if. In other words, these phrases are used to indicate that if a certain event (the one specified by a verb in the subjunctive mood) does not occur, then another event (using a verb in the indicative mood) will (or would, if the conditional tense is used). Here are some examples using a menos que: A menos que tengas pasià ³n en lo que haces, no vas a ser feliz. Unless you have passion about what youre doing, youre not going to be happy. No aprobars a menos que estudies mucho. You wont pass unless you study a lot. A menos que el mundo despierte, la humanidad no tiene futuro. Unless the world wakes up, humanity doesnt have a future. Generalmente no tengo problema a menos que coma alguna comida picante. Generally I dont have a problem unless I eat spicy food. A menos que estuviera muy enojado, llorarà ­a. Unless I were very angry, I would cry. No podemos tener salud a menos que bebamos unos ocho vasos de agua al dà ­a. We cant be healthy unless we drink some eight glasses of water a day. A no ser que is used in the same way and is nearly always interchangeable with a menos que: Va a ser difà ­cil, a no ser que nieve bastante. Its going to be difficult, unless it snows enough. La vida no es buena a no ser que uno tenga dinero. Life isnt good unless one has money. No tendremos à ©xito a no ser que tengamos una visià ³n global. We wont have success unless we have a global vision. La vida no es aceptable a no ser que el cuerpo y el espà ­ritu vivan en armonà ­a. Life isnt acceptable unless the body and spirit live in harmony. These phrases can also be used along with commands instead of a verb in the indicative in the independent clause: No lo haga a menos que comprenda todos los riesgos. Dont do it unless you understand all the risks. Cà ³mpralo, a no ser que tengas dudas. Buy it, unless you have doubts. Spanish also has several other less common phrases that have much the same meaning, as shown in boldface in the sentences below: Un cuerpo permanecer en un estado de reposo o de movimiento uniforme, a menos de que una fuerza externa actà ºe sobre à ©l. A body will remain in a state of rest or steady motion, unless an external force acts on it. Se recomienda no utilizarlo a reserva de que sea claramente necesario. Using it is not recommended unless it is clearly necessary. De no ser que lleves ya una dieta muy bien equilibrada, ser mejor que sigas estes consejos. Unless you follow a very balanced diet, it will be better if you follow this advice. Llegaremos a las nueve salvo que el autobà ºs se retrase. We will arrive at 9 unless the bus is late.