Write an article based on this "Find the direction of the force vector and the direction of motion. Find the displacement of your object. Find the force on the object. Multiply Force Distance. Label your answer in joules."
To start, it's important to first be able to identify both the direction the object is moving in and the direction from which force is being applied. Keep in mind that objects don't always move in line with the force being applied to them for instance, if you pull a small wagon by its handle, you're applying a diagonal force (assuming you're taller than the wagon) to move it forward. In this section, however, we'll deal with situations in which the force and the object's displacement do have the same direction. For information on how to find the work when these things don't have the same direction, see below. To make this process easy to understand, let's follow along with an example problem. Say that a toy train car is being pulled directly forward by the train in front of it. In this case, both the force vector and the direction of the train's motion point the same way forward. In the next few steps, we'll use this information to help find the work done on the object. The first variable we need for the work formula, D, or displacement, is usually easy to find. Displacement is simply the distance that the force has caused the object to move from its starting position. In academic problems, this information is usually either given to or is possible to deduce from other information in the problem. In the real world, all you have to do to find displacement is measure the distance the object travels. Note that measures of distance must be in meters for the work formula. In our toy train example, let's say that we're finding the work performed on the train as it travels along the track. If it starts at a certain point and ends at a spot about 2 meters (6.6ft) up the track, we can use 2 meters (6.6ft) for our "D" value in the formula. Next, find the magnitude of the force being used to move the object. This is a measure of the "strength" of the force the bigger its magnitude, the harder it pushes the object and the quicker it accelerates. If the force's magnitude isn't provided, it can be derived from the mass and acceleration of the moving (assuming that there aren't other conflicting forces acting on it) with the formula F = M A. Note that measures of force must be in newtons for the work formula. In our example, let's say that we don't know the magnitude of the force. However, let's say that we do know that the toy train has a mass of 0.5 kilograms and that the force is causing it to accelerate at a rate of 0.7 meters/second2. In this case, we can find the magnitude by multiplying M A = 0.5 0.7 = 0.35 Newtons. Once you know the magnitude of the force acting on your object and the distance it's been moved, the rest is easy. Simply multiply these two values by each other to get your value for work. It's time to solve our example problem. With a value for force of 0.35 Newtons and a value for displacement of 2 meters (6.6ft), our answer is a single multiplication problem away: 0.35 2 = 0.7 joules. You may have noticed that, in the formula provided in the intro, there's an additional piece to the formula: Cosine(). As discussed above, in this example, the force and the direction of motion are in the same direction. This means the angle between them is 0o. Since Cosine(0) = 1, we don't need to include it we're just multiplying by 1. In physics, values for work (and several other quantities) are almost always given in a unit of measurement called joules. One joule is defined as one newton of force exerted over one meter, or, in other words, one newton meter. This makes sense since you're multiplying distance times force, it's logical that the answer that you get would have a unit of measurement equal to multiplying the units of your force and distance quantities. Note that joules also has an alternate definition one watt of power radiated over one second. See below for a more detailed discussion of power and its relationship to work.