Example: A Block On An Inclined Plane
A simple free body diagram, shown above, of a block on a ramp illustrates this.
- All external supports and structures have been replaced by the forces they generate. These include:
-
- mg: the product of the mass of the block and the constant of gravitation acceleration: its weight.
- N: the normal force of the ramp.
- Ff: the friction force of the ramp.
- The force vectors show direction and point of application and are labeled with their magnitude.
- It contains a coordinate system that can be used when describing the vectors.
Some care is needed in interpreting the diagram. The line of action of the normal force has been shown to be at the midpoint of the base but its true location can only be found if sufficient further data is given. The diagram as it stands would need to be modified were we told that the block is in equilibrium.
There is a potential difficulty also with the arrow representing friction. The engineer who drew this diagram has used the tip of the arrow to indicate the point of application of a force. (See the other force arrows in the diagram). Now, the tip of the friction arrow is at the highest point of the base. The intention however is not to indicate that the friction acts at that point. The engineer in this instance has assumed a rigid body scenario and that the friction force is a sliding vector and thus the point of application is not relevant. The engineer has tried to indicate that the friction acts all along the whole base by drawing an arrow all along the base but such artistic ploys are a matter of personal choice.
Read more about this topic: Free Body Diagram
Famous quotes containing the words block, inclined and/or plane:
“The chess pieces are the block alphabet which shapes thoughts; and these thoughts, although making a visual design on the chess-board, express their beauty abstractly, like a poem.... I have come to the personal conclusion that while all artists are not chess players, all chess players are artists.”
—Marcel Duchamp (1887–1968)
“As to the thirty-six Senators who placed themselves on record against the principle of a World Court, I am inclined to think that if they ever get to Heaven they will be doing a great deal of apologizing for a very long time—that is if God is against war—and I think He is.”
—Franklin D. Roosevelt (1882–1945)
“Even though I had let them choose their own socks since babyhood, I was only beginning to learn to trust their adult judgment.. . . I had a sensation very much like the moment in an airplane when you realize that even if you stop holding the plane up by gripping the arms of your seat until your knuckles show white, the plane will stay up by itself. . . . To detach myself from my children . . . I had to achieve a condition which might be called loving objectivity.”
—Anonymous Parent of Adult Children. Ourselves and Our Children, by Boston Women’s Health Book Collective, ch. 5 (1978)