Saturday, October 11, 2014

Inclines Video

Watch my latest video for AAPT Films (above). You can help your students understand a topic that gives many students trouble: Inclines. Many students struggle with learning inclines, so how can we introduce this concept convincingly? Learn how in the next seven minutes!

Use experiment to help students understand inclines!

You can start by showing students a frictionless situation. In this case, the gravity that is pulling it down the hill is weakened by the flatness of the slope. 


The acceleration due to gravity is weakened by a factor that depends on the angle.  Can you imagine a function of theta, that starts off at zero then grows to its maximum at 90 degrees?  Why yes, its sine.

I do this lab in my introduction to trigonometry unit.   It’s

 called diluting acceleration


When it comes to forces on inclines, here are a few tips.

You will want to introduce this AFTER you have discussed 

friction on a flat surface, and of course Newton’s Laws, 

especially Newton’s 3rd Law.  That’s because the normal 

force is often an equal and opposite reaction to other forces.  


In most cases, friction opposes motion, so if the block was 

sliding down the hill, the friction – kinetic friction- would be 

up the hill, and if the block was sliding up the hill, the 

friction would be down the hill.  

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