## Equilibrium Practice Test Answers

MC

- C
- C
- C
- C
- B
- *A – this one is a bit more challenging. You need to do two steps. First find F, then find frictional force.
- A
- D
- A
- * the force labeled ‘F’ is 62N. The force it asked for though (at the fulcrum) is actually 146N, which isn’t really an option.

## Static Equilibrium

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

## Torque From Angled Force

Practice: WS2 # 5, 6, 7, 8… read more

## Torque?

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

## Equilibrium: Introductory Topics

We will be doing a unit on equilibrium. This was actually explored in our dynamics and forces unit. To review what equilibrium means:

https://www.flippingphysics.com/equilibrium.html

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:

https://www.flippingphysics.com/center-of-mass.html

Here is a sample problem showing how we solve for translational equilibrium.… read more

## Energy Review

Here is the Flipping Physics energy review video:

https://www.flippingphysics.com/ap1-work-review.html

And here are the answers to the practice test:

- B
- A
- C
- B
- B
- C
- C
- Top-right one

Written response:

- 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.

## Energy

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

## Energy Basics

You should be well-grounded in the basics of energy. Here is all the theory you are responsible for at this point:

What is work? The cosine term in the equation is not strictly necessary as long as you understand the force to be in the direction of motion.… read more

## Physics Review

Your dynamics test is on Friday now!

Here’s a pdf of my solutions to the practice assignment. Please remember that your test will be very similar in form and content. Sorry for the errors.

Next up, here are the answers to the longer practice test:

- C
- C
- C
- A
- B
- C
- D
- D
- C
- D

Written section:

- A.

## 2 Problems

Dynamics test on Thursday!

… read more