Category: Unit 2: Dynamics

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11/15 Quiz on forces; homework

  • You will be able to use the green AP Physics 1 equation sheet for the quiz.
  • You will need a scientific calculator.
  • The quiz consists of two problems, one on each side of the sheet.

To prepare for next week’s test, be sure to review the video tutorials here.

If you don’t have a scientific calculator by the test next week, I will be happy to provide you with a table of trigonometric identities and teach you how to use it (I guess I’m a dinosaur–this is how I learned to do SOHCAHTOA, and we didn’t call it that).

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19-11-14: A few force videos

Video list

The videos today are all from Flipping Physics.

  • Introduction to Free Body Diagrams or Force Diagrams
  • 5 Steps to Solve any Free Body Diagram Problem
  • A Three Force Example of Newton’s 2nd Law with Components
  • AP Physics 1: Dynamics Review (Newton’s 3 Laws and Friction)

Remember that as you watch these videos, when a problem/question is presented, try writing out the answer before you continue with the video–then check yourself as you progress through the video.

Flipping Physics: Introduction to Free Body Diagrams or Force diagrams

Produced by Flipping Physics
Continue reading “19-11-14: A few force videos”
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19-11-14 Getting ready for forces quiz

Today’s assignment from textbook:

p. 110-112: 20, 37, 38, 39, 41 and 51.

What you need to know for tomorrow’s quiz:

  • Use of first five equations in your equation sheet
  • Draw force diagrams
  • Evaluate forces to determine balanced/unbalanced net force
  • Special circumstances/types of problems
    • Solve problems with pulleys (pulleys change direction of tension, not magnitude)
    • Solve problems with ramps
  • Solve problems with forces at angles
    • Break down forces into x and y components
    • Solve triangle math using SOHCAHTOA and law of sines

Additional resources

You an find instructional/tutorial videos here.

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11/13 Force diagrams: Two solved problems

Force diagrams, or Free Body Diagrams, are sketches we use in physics to show forces applied to an object or system of objects.

Here are a couple of videos I created to help walk you through some complicated problems. I encourage you to pause them as you go through and see if you can determine the ‘next move.’

Problem A

A 13 kg block of wood slides across the floor with constant speed when it is pulled with a horizontal force of 32 N. What is the friction constant, µ, between the wood and the floor?

Problem B

A block is sliding up a wall with a constant velocity, and a force applied upwards at an angle. Here is a sketch:

sketch showing the box on the wall with the unknowns labeled.
As with many AP questions, you are asked to solve for one variable in terms of the others. In this case, your final equation should be in the form F = (an expression that includes m, μ , and θ )