Hewitt Drew-It! PHYSICS Screencasts
Newton's First Law—Inertia

1. Equilibrium Rule
(Paul G. Hewitt explains equilibrium by drawing so everyone can understand this topic.)
End Question: If Burl and I both stood at a far end of the scaffold, and leaned outward a bit so the opposite rope went limp, what would be the tension in our supporting rope?

2. Equilibrium Problems
(Paul shows numerical values for the billboards cast.)
End Question: What is the tension, in newtons, in the right-hand rope

3. Net Force and Vectors
(Box of candy to Nellie hanging by vertical ropes.)
End Question: Will the vectors representing rope tensions (vertical ropes of different lengths) still each be 150 N? And can you defend your answer

4. Nellie’s Rope Tensions
(Nellie introduces parallelogram rule, then hanging by ropes at angle.)
End Question: Suppose we replace this right-hand rope with a shorter rope — with a much steeper angle. Does the rope tension in the longer left-hand rope increase, decrease, or remain the same? Can you defend your answer?

5. Nellie’s Ropes
(Tensions via Nellie hanging by non-vertical ropes.)
End Question: By way of strings and pulleys, a pair of 10-N blocks pull on a scale as shown. What’s the reading on the scale?

6. Force Vector Diagrams
(Paul extends Jim Court diagrams, identifying forces on a suspended, then falling ball.)
End Question: [In regard to a falling ball; If air resistance becomes as great as the ball’s weight, is the ball then in equilibrium? What do we say about its motion at this point?

7. Force Vectors on an Incline
(Paul analyzes forces acting on a block on an inclined plane, leading to forces on a block sliding on a curved surface.)
End Question: At which location, A, B, or C, will the acceleration along the ramp be greatest?

16. Newton's Laws of Motion
Paul enlists Nellie Newton to illustrate Newton's three laws of motion.