The system is setup with a projectile launcher aimed at a target some distance away. When the ball is shot, it travels through a photogate which senses the interruption and releases the target. As both fall at the same rate the ball travels horizontally and hits the target in the air.
* Equipment seen in the video may vary from equipment used in ND Demonstrations. See information and images below for ND equipment and setup.
Setup:
Mount the projectile launcher on the lab table using a clamp. Mount the photogate across the barrel of the launcher. Connect the photogate to the control box. With the control box disarmed, connect the power to it and connect it to the drop box. Use a ring stand to mount the drop box across the room. Hang the target from the drop box. Place a foam block below the target. Use the laser on the launcher to align the launcher with the target. (It should be centered on the target as it hangs.) Place the ball in the launcher and use the rod to push it to the desired range. Arm the control box. Pull the string on the launcher to fire the ball and drop the target. The ball should hit the target in mid air.
Notes:
Test this demonstration ahead of time to ensure the correct range is chosen. For a more satisfying time of flight of the projectile, a longer cable (20+ ft) will need to be used to attach the control box to the drop box.
Courses Used In:
PHY 10111
PHY 10310
PHY 10410
PHY 30210
Discussion and Polling Questions:
(Before demo) In order to hit the target, where should we aim? Above, below, or on target?
To really ask a trick question, don't explicitly mention the third option. If you'd like, go through the other two options first and show that they don't work. Then, you can propose the third option or someone in the class might figure it out by then as well.
Do the masses of the objects matter?
Does the initial velocity of the projectile affect whether or not it will hit?
If so, how does it affect it?
If not, what does it affect?
Where would we need to aim if the falling object starts falling before we launch the projectile? What about after?
Equipment Needed: (Shelf 13 drawer)
Projectile Launcher with Laser Alignment
Ball
Control Box with Power Adapter
Photogate with Cable
Drop Box with Cable
Target
Foam Block
Ram Rod
Clamps
Ring Stand