# 2D MOTION

1D15.10 ULTRASONIC RANGER (Renumbered by PIRA to 1C10.05)
1D50.10 BALL ON STRING
1D50.40 PAIL OF WATER
1D60.10 HOWITZER AND TUNNEL
1D60.20 TWO BALL DROP (Simultaneous Fall)
1D60.30 TARGET DROP (aka Monkey Shoot)
1D60.35 RANGE OF PROJECTILES
1D60.40 LIQUID NITROGEN CANNON
2B30.70 See for another projectile motion demonstration.

 1D15.10/1C10.05 Ultrasonic Ranger Use ultrasonic ranger and computer to measure x,v and a of a student or other moving object.   Setup Requirements: Advance preparation needed. Teacher needs to know how to use computer setup and Science Workshop / Data Studio. Software may not be on computer in classroom. May need to set up on cart before class using computer in Demo Room.   Equations: 1D Motion Equations   Safety Issues: Avoid bumping into things while moving around in front of ultrasonic ranger.

 1D50.10 Ball On a String Tie ball on a string and twirl in circle to demonstrate centripetal acceleration and centripetal force. Setup Requirements: Various size and color balls available. Equations: a = v2/r Safety Issues: Ball may come loose.

 1D50.40 Pail of Water Swing pail partly filled with water or pieces of plastic in a vertical circle. If moved fast enough the material will not fall out when overhead. Setup Requirements: Use water or pieces of plastic depending on how much confidence you have in yourself and the laws of nature (which includes Murphy's Law).   Equations: a = v2/r     Safety Issues: Wet Teacher

 1D60.10 Howitzer You give the cart a shove.You either jerk on a cord to pull out the pin or tie string to a rod so the pin is pulled out when the cord straightens. Ball is fired vertically from a moving cart and falls back into muzzle. If air resistance can be ignored the ball will keep its initial foward speed while in the air. Setup Requirements: Practice recommended. Lubricate pin shortly before using. Install something soft around opening so ball will not hit metal and bounce off.   Equations: If air resistance can be ignored, horizontal and vertical motion are independent.   Safety Issues: Place something to keep cart from rolling off table.

 1D60.20 Simultaneous Fall or Two Ball Drop If air can be ignored horizontal and vertical motion are independent. Place balls on device. Flip lever to fire.Two balls simultaneously dropped with one projected horizontally hit the floor together. They fall the same amount in same time before hitting floor. Retrieve balls before proceeding with class. Setup Requirements: Attach device to rod and place on edge of front desk.   Equations: a=g for y component of both balls. X component is irrelevant.   Safety Issues: Align so ball will not head toward students.

 1D60.30 Target Drop (aka Monkey Shoot) Target is released at the same time as the projectile from a blow gun. Projectile hits target in midair. If the target stays in place the projectile will miss becaused it is falling under gravity as it heads to the target. This is commonly called Monkey and Hunter or Monkey Shoot.     Setup Requirements: Advance noticed needed. Unless you have an 8AM class it may be necessary to set up on carts to save time.Tube (gun) needs to be adjusted by user so it points st target. Test to see if can falls as soon as power turned off. If not put weights in can (~ 100 grams).   Equations: a=g for y component of both ball and target. Non-zero x component of velocity only for ball.   Safety Issues: Metal ball bouncing off can and hitting student. Overheating coil if batteries left connected.   Additional Instructions When ready to do demo: 1. Look through tube and move it so you see target. 2. Put ball in tube. It may be necessary to bend piece of metal at end of tube for better electrical contact. 3.Turn on power using switch on box. 4.Hang target from electromagnet. 5. Disconnect one end of yellow wire connected to tube terminals. 6. Blow through tube. 7. Find ball. 8. To repeat reconnect yellow wire and go to step 1 9. When finished turn off power to avoid overheating coil and draining battery.

 1D60.35 Range of Projectile A device is available to show how range varies with angle. Projectile falls on desk. Put something on desk to mark where projectile lands for different angles.   Setup Requirements: Needs to be attached to corner of front desk. Need something to mark where ball hits. Ask ahead of time about how it works.   Equations: Range proportional to sin (2 x Angle)   Safety Issues: Being hit by ball. Aim away from students. Cover electronic equipment.

 1D60.40 Liquid Nitrogen Cannon Put a small amount of liquid nitrogen in bottom of tube. Insert cork. A hammer may be needed due to pressure. Quickly move clear. Use as dramatic visual aid when discussing projectile motion. Setup Requirements: At least 2 working days notice required or bring your own LN.   Equations: Projectile Motion Equations   Safety Issues: Wear eye protection. Do not point at students. Gloves available.

 2B30.70 Vacuum Bazooka A ball placed in the left end is moved through due to the low pressure area created by the vacuum cleaner and comes out the other end either knocking the cap off or tearing through thin paper. Use as attention getting device when talking about 2 dimensional motion. The device can also be used when talking about the force exterted by a pressure. That is why it has been put in this PIRA category.         Setup: Assembled as needed. Practice ahead of time. A plastic cap or thin paper is placed over one end so that end will have low pressure area and air only moves into device through other end.   Equations: 2 dimensional motion equations or P = F/A.   Safety Issues: Point so ball and cap will not hit students or equipment. Best used in Parker 307 due to extra space.