# a free body diagram includes which of the following

Significance The object under consideration in each part of this problem was circled in gray. When you are first learning how to draw free-body diagrams, you will find it helpful to circle the object before deciding what forces are acting on that particular object. This focuses your attention, preventing you from considering forces that are not acting on the body. Two Blocks in Contact A force is applied to two blocks in contact, as shown. Strategy Draw a free-body diagram for each block.

Block on the Table Coupled Blocks A block rests on the table, as shown. A light rope is attached to it and runs over a pulley. The other end of the rope is attached to a second block. The two blocks are said to be coupled. Block m 2 m 2 exerts a force due to its weight, which causes the system two blocks and a string to accelerate. Strategy We assume that the string has no mass so that we do not have to consider it as a separate object.

Find the force acting on the car as a function of position. Two boxes, A and B, are at rest. Shown below is a The block is held by a spring that is stretched 5. What is the force constant of the spring? In building a house, carpenters use nails from a large box. The box is suspended from a spring twice during the day to measure the usage of nails. At the beginning of the day, the spring stretches 50 cm. At the end of the day, the spring stretches 30 cm.

What fraction or percentage of the nails have been used? The incline is frictionless. Two forces are applied to a 5. If one of the forces acts in the positive x -direction with magnitude Draw free-body diagrams for each block. If two tugboats pull on a disabled vessel, as shown here in an overhead view, the disabled vessel will be pulled along the direction indicated by the result of the exerted forces.

Assume no friction or drag forces affect the vessel. Why or why not? Show Solution. Then a force acts on it for 2. What are the magnitude and direction of the average force that acted on the object over the 2. Write an expression for the total distance the body travels in terms of the variables indicated.

The velocities of a 3. If the object is moving at constant acceleration, what is the force acting on it? A kg astronaut is riding in a rocket sled that is sliding along an inclined plane. The sled has a horizontal component of acceleration of [latex] 5. Calculate the magnitude of the force on the rider by the sled.

Hint : Remember that gravitational acceleration must be considered. The internal arrangement does not matter for the determination of the supporting reactions! AND, if the supporting and loading geometries are the same, the external reactions will alsways remain the same. It looks like many lamps found all over the world. The three photos illustrate how the free body diagram for this structure should be conceived. The first step is to dematerialize the lamp.

Identify the center of the body and draw this as a straght line. The only identifieable weight is the lamp, so this is drawn as a vector as indicated. The next step is to determine what is required at the other end of the lamp to maintain equilibrium; what is needed to keep the lamp from spinning off into space? These forces including the moment are drawn as indicated. What is missing from this illustration? The magnitudes of the moment and force at the left side should be included in a complete free body diagram.

The Verona Column There are many situations in which the exact conditions of the end restraints are not able to be determined in the first glance. This is a thin brick column supporting a wooden canopy at the old castle in Verona, Italy. How is this element connected to the wall below? The weight of the object acts as a force pointing vertically downward, and the presence of the cord indicates a force of tension pointing away from the object. Object A has one interface and hence experiences a normal force, directed away from the interface.

The source of this force is object B, and this normal force is labeled accordingly. Since object B has a tendency to slide down, object A has a tendency to slide up with respect to the interface, so the friction f BA is directed downward parallel to the inclined plane.

As noted in step 4 of the problem-solving strategy, we then construct the free-body diagram in Figure 5. Object B experiences two normal forces and two friction forces due to the presence of two contact surfaces. The object under consideration in each part of this problem was circled in gray. When you are first learning how to draw free-body diagrams, you will find it helpful to circle the object before deciding what forces are acting on that particular object.

This focuses your attention, preventing you from considering forces that are not acting on the body. T he free-body diagram above depicts four forces acting upon the object. Objects do not necessarily always have four forces acting upon them. There is no hard and fast rule about the number of forces that must be drawn in a free-body diagram. The only rule for drawing free-body diagrams is to depict all the forces that exist for that object in the given situation.

Thus, to construct free-body diagrams, it is extremely important to know the various types of forces. If given a description of a physical situation, begin by using your understanding of the force types to identify which forces are present. Then determine the direction in which each force is acting.

Finally, draw a box and add arrows for each existing force in the appropriate direction; label each force arrow according to its type. You get force direction. Then only look at the person, now you can get hand forces. Now only look at the arm to get the shoulder forces and moments, and on and on until the component you intend to analyze is exposed. Typically, however, a provisional free body sketch is drawn before all these things are known. After all, the whole point of the diagram is to help to determine magnitude, direction, and point of application of the external loads.

Thus when a force arrow is originally drawn its length may not be meant to indicate the unknown magnitude. Its line may not correspond to the exact line of action.

Even its direction may turn out to be wrong. Very often the original direction of the arrow may be directly opposite to the true direction. External forces known to be small that are known to have negligible effect on the result of the analysis are sometimes omitted, but only after careful consideration or after other analysis proving it e. The external forces acting on the object include friction , gravity , normal force , drag , tension , or a human force due to pushing or pulling.