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Physics Lab: Playing with a Fan Cart
In physics labs, we have been using low friction carts with fans for a long time. A very long time. However, I was never a fan of the old fans. Yes, they pushed the cart to make it accelerate and that’s nice. But they weren’t that strong and not always consistent.
We’ve been using the new Vernier Cart Fan. It’s a rechargeable fan that attaches to the cart. It has 4 different force settings with four different run times (with a 3 second countdown). The fan mount allows the force from the fan to be angled with respect to the motion of the cart (nice). Oh, you can even put two more fans on the same cart.
This is not a sponsored post, I just really like that fan. OK, let’s do some experiments.
Is the Force Constant?
I have my cart with the fan and it has a mass of 448.37 grams. Let’s put the fan on force setting two and just let the cart accelerate. In one dimension (let’s call it the x-direction) we can write Newton’s second law as:
The Go Direct Sensor cart measures the position of the cart and from that you can get the velocity as a function of time. Recall that the acceleration is defined as:
This means that with a plot of velocity vs. time, the slope of the linear function will be the acceleration. I’m going to drop the “x” subscript since…
