- *A – this one is a bit more challenging. You need to do two steps. First find F, then find frictional force.
- * the force labeled ‘F’ is 62N. The force it asked for though (at the fulcrum) is actually 146N, which isn’t really an option.
Here is a rotational equilibrium problem
Note that you use both translational and rotational equilibrium! Also, you can pick your axis of rotation, so why not choose a location to eliminate unknown torques.
Here is the classic “ladder problem” – and they show a different way to calculate torques: instead of multiplying the perpendicular component of the force by the distance it acts at, you can multiply the entire force by the perpendicular distance between that force and the axis of rotation.… read more
Practice: WS2 # 5, 6, 7, 8… read more
We are beginning with the fundamentals. An easy start: WB section 5.3 # 4, 6
Also… have your percent test corrections done by tomorrow!… read more
Practice exercises from today: Worksheet 1 # 1-4, 6, 7
Torque is the rotational equivalent of force – just like angle (degrees, radians) is the equivalent of distance. To calculate torque we must first identify the axis of rotation – the “center” that the torque is causing a rotation around.… read more
We will be doing a unit on equilibrium. This was actually explored in our dynamics and forces unit. To review what equilibrium means:
One important thing to remember is that when we treat an object as a single mass (instead of a whole bunch of matter stuck together, which most things actually are) we simplify it as though it were a single point at its center of mass:
Here is a sample problem showing how we solve for translational equilibrium.… read more
Here is the Flipping Physics energy review video:
And here are the answers to the practice test:
- Top-right one
- a) 12000 J (11594 J) b) 190 N
- a) 2.2 m b) same height c) because there is no friction so track length irrelevant, only the height matters (work done against gravity is only in vertical direction)
- If you do this as only an energy problem: 150 m.
Your energy test is on Monday – second block. We’ll do some last-minute review during the first block.
Today I assigned # 5, 3, 7, 9, 10, 13, 15 from the worksheet. Tomorrow we’ll do some more review work and you’ll have practice to work on this weekend.… read more