Projects: LOOPS : Topic 7 Force and Motion in One Dimension
This page last changed on Jul 07, 2008 by kbell.
*Classroom discussion: * There are three new ideas to be added to the content of last week:
Of these, hardest by far is to recognize that forces can be balanced even when an object is moving. The best way to discuss these concepts is by recalling, explaining, and demonstrating some examples that are likely to be familiar to the students. Here are some examples:
Some situations of one-dimensional accelerated motion should also be demonstrated and discussed. In each case, emphasize the connection between the change in speed and the direction and magnitude of the force. We could easily make simulations of each of these, or use PhET ones.
Investigations: Have the students produce simulations (using our version of SimCalc) of some or all of the familiar examples of constant or accelerated motion discussed in class. The simulations should include all the forces acting on the moving object (so in the case of the first example, the boat should have a force due to gravity that is cancelled out by a buoyant force, and a force due to the motor that is cancelled out by the drag caused by its motion through the water) and the motion of the object should include acceleration or not, as discussed in class. It might be best to break the class into small groups, and assign one example to each group. The group is given 20 minutes, say, to produce the simulation, at which point each group will be called upon to demonstrate and describe its example to the rest of the class. (As usual in such situations, the individual chosen to give the presentation will be selected at random by the teacher from among the members of each group, and group's performance (and grade) will be judged on the basis not only of the completeness of the simulation but also on the skill and knowledge of the presenter.) It might also be a good idea to have each group write an "annotation" for its example prior to the presentation to the class, with the option to revise the annotation based on comments during the presentation. We'd keep track of both versions, of course, and report them to the teacher.
Extensions: Challenge students to come up with examples of their own and build animations representing them. The examples should illustrate either balanced forces acting on a body in motion, unbalanced forces acting on a body in rotational motion at constant speed, unbalanced forces acting to accelerate or decelerate an object but keep it moving in the same direction, or the effect of increasing or decreasing the mass of an object while keeping constant the force applied to it.
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