What's on the test?
Test format:
- 1 page with three conceptual questions
- 1 projectile motion problem
- 1 Newton's Laws problem
- 1 more Newton's Laws problem
Helpful Hints
Practice practice practice! The more questions and problems you do, the better.
The book's full of them. Doing problems is much better than reading the text - if you find problems you can't do, then read.
Make sure you're familiar with all the equations on the equation sheet. You should know what you can do with each one, and what the limitations are (if any).
During the exam
- Manage your time appropriately. You have over 20 minutes per problem, which should be ample time to work through these problems.
- Take the time to organize the data, to draw free-body diagrams, and to show your coordinate system.
- SHOW YOUR WORK. A correct method with an incorrect numerical answer is worth more than a correct answer that appears out of nowhere.
- Check your answers. There is usually more than one way to do a problem.
Projectile Motion Problems
Follow these steps:
- Draw a diagram, if one is not drawn already. If there is one, feel free to add things to it.
- Choose an origin and positive directions for your coordinate system.
- Create a table showing all the x-data in one column and all the y-data in another. Split the initial velocity into components.
- Keep the x-data separate from the y-data. The link between them is time.
- Then look at the equations to see how to proceed.
Newton's Laws Problems
Generally this means Newton's Second Law. Follow these steps:
- Draw a free-body diagram for each object in the system.
- Think about what the system will do. Try to determine which way the system will accelerate (if it does).
- Choose coordinates systems for each object. The coordinate systems do not have to be the same, but they must be consistent with one another. Align them with the acceleration.
- Split all forces into components.
- Apply Newton's Second Law twice, once for each direction, for each object.
This means writing down, for example, ΣFx = max
Look at the free-body diagram to work out the left-hand side of the equation.
Watch your signs.
- In a circular motion problem, a = v2/r
- Put the equations together to eliminate unknowns and (usually) to solve for acceleration.