Forces and Motion

Honors Physics and Introductory Physics jumped into the arena of forces yesterday, with a look at the nature of forces, the ability to combine force vectors to find net force and the use of free-body diagrams to analyze the forces acting on an object. Honors Physics took a harder look at calculating net force and those folks should be able to combine any and any number of force vectors to determine F_net. We'll look at how to use that to assess an object's acceleration next week. For Introductory Physics, be able to calculate F_net for forces that are in the same direction or opposite directions and be sure you are clear about the distinction between balanced and unbalanced forces. For both groups, don't lose sight of the meaning of F_net = 0 N. It means no net force, balanced forces, no acceleration and object moves with constant velocity. Also for both groups, remember that only forces that act directly on an object are included in free-body diagrams, not forces that the object applies to other objects. Next week, Introductory Physics takes a look at friction and Honors Physics steps into Newton's laws of motion.

Physics A and B both worked on evaluating horizontally-launched projectiles. For horizontally-launched projectiles, remember that some information important for problems solving won't be directly stated in the problem. The fact that the initial velocity in the y-direction is 0 m/s and the velocity in the x-direction is constant (and the stated launch velocity), won't be spelled out for you. Also, remember that accelration in the y-direction is -9.81 m/s² and is 0 m/s² in the x-direction. The time you calculate for the object to hit the landing point is the same time as for the ball to cover the horizontal range. You need all that information in your pocket, along with any explicit information in order to work these problems. We'll go over the homework items on Wednesday when we return from the extra-long weekend and then add a layer of complexity by tackling projectiles launched at an angle.