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course Phy 201
3/7/13 245pm
Cannonball MotionPhysics I Assignment 08: Set the cannon to fire at 70 degrees, at 20 meters / second. Hold your index finger straight up and move it from left to right, keeping it just ahead of the projectile. Try this a few times until you get the 'feel' of the left-to-right motion (click the 'erase' button between trials so you can see the motion). Does your finger speed up or slow down?
Now hold your index finger horizontal, parallel to the floor, and similarly trace the up-and-down motion of the projectile. Does your finger speed up or slow down, and if so where does it do each?
How do you think the acceleration and velocity vectors would behave for this motion?
Submit a copy of your results and insights using the Submit Work Form, with title 'Cannonball Motion'
When moving my vertical finger left to right I couldn’t tell much difference in speed.
I could tell more of a difference when my finger was horizontal. It was faster as it came out of the cannon, then slowed down as it reached its apex and then sped up as it moved towards the ground.
The velocity would closely follow the direction of the cannonball at any instant.
Gravity would always be pulling the cannonball down at 9.8m/s^2 but I don’t think the acceleration vector would point straight down the whole time. I’m not sure what it would look like.
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Good.
As you will find plausible from your observations, the horizontal motion of the cannonball is at constant velocity. It therefore experiences zero acceleration, and thus zero net force, in this direction.
The vertical acceleration is always downward (slowing the rising cannonball and speeding up the falling cannonball).
Since the horizontal acceleration is zero, the only acceleration is the vertical acceleration, so the acceleration vector would in fact point straight down.
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