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Physics On Ice: A Field Trip on Force and Motion

Margaret Scora, Teacher at M. Paul Dwyer CHS, Oshawa ON

Taking a class to Wonderland™ to investigate force and motion can be an expensive and frustrating adventure. The local ice rink is probably only 15 minutes away for most of us, a lot cheaper, and you can be there and back in less than three hours with a whole lot of new experiences for your students to ponder and discuss.

Why an ice rink?
Friction…. or the lack thereof. Not perfect by any means but pretty decent. Cheap! In our board it costs $100 for the bus and approximately $150 for two hours of ice time. One bus load and $6 or $7 per student covers the lot!

Physics On Ice from OAPT Newsletter on Vimeo.

The first time you run the trip will be the most work (as always). Not all your students might have skates but there are still many useful things they can try or observe. However, there are some preparations that need to be made with regards to safety.

Excursion requests, as per usual. Talk to your department head and principal of course to sell the deal. Invite them along! You probably want at least one supervisor that can skate. I can skate (not super well) but enough that I can stop without hurting anyone. Book your excursion either for the morning before lunch, or after lunch so you don’t have to worry about food. After lunch you run in to the possibility of more competition for your ice time or your buses. Book early and no worries!

Book your ice time. Ask your phys. ed. department or administrator about which rink is best. You will want to have a conversation with the Rink Administrator or Booking Facility about the “Conditions of Use”. You will need to explain to them what you are doing and why and that everyone will be wearing a helmet. Below is the addition I have to the “conditions clause”.

This is a Physics Class Investigation. Some students skate and some walk in good supportive footwear. All footwear must be clean and free of debris. The students push blocks or pucks on the ice, roll balls, slide on crazy carpets and roll on a wheeled cart on the ice. There is one activity where the students will have sandpaper attached to their shoes to show the difference in friction. All students will have helmets while on the ice surface.

Permission forms. A little extra is needed here since you are going to an ice rink. I usually put an additional bit* on my permission forms regarding safety. See paragraph following:

For this trip to the ice rink you must wear pants. Bring warm clothes and gloves. CSA approved helmets* are required for all students on the ice. *These include hockey, bicycle or ski/snowboard helmets. In order for the students to be allowed on the ice they must have skates or runners or sturdy walking shoes. No dress shoes, ballet slippers etc. are allowed on the ice. This is not a recreational skating period; it is a physics class. Other materials required: pen, pencil and eraser.

When you are collecting funds and permission forms you also need a checklist of who has a helmet. Normally the students can borrow one, but if you need a couple check with your Phys. Ed. Department.

Also, in my board the students have a whole set of forms to fill out because of the local concussion policy. Check with your VP whether or not this is necessary or can be simplified as it is only for two hours!

Bus: Order an Activity Bus. This means you will have space to store stuff in the bins outside the bus. See item 5 for the list of things I bring.

What I bring:
  • A box of pucks. Your school’s hockey team can lend you some (20-30 is nice) or you can buy a bunch at Play It Again sports for cheap (around a dollar apiece).
  • Pylons. For the obstacle course activity. About 10 to go across the blue line. Again ask Phys. Ed.
  • Hockey sticks. I usually borrow about 10 floor hockey sticks from Phys. Ed. for 1 busload. I also allow the students to bring their own hockey sticks but they are under strict rules.
  • Crazy carpets and skipping ropes, the sturdy kind. Yup, a couple of these are great. Students can pull each other on the carpets that way.
  • A four-wheeled cart or a skateboard. No kidding. No one is allowed to stand on it though. Only sitting and being pulled with a rope or pushed on the back from behind. I actually have a four-wheeled cart and a skateboard. Sometimes Canadian tire has carts on sale. I took the handle off mine.
  • A torque wheel (bicycle wheel with handles).
  • Medicine balls. Two or three from Phys. Ed. should do the trick.
  • Sandpaper for sandpaper shoes. I only take two pieces (large grit). My tech department usually provides this.
  • Duct tape! For the sandpaper shoes and taping pucks together to make a stack.
  • Force scale. I have one big one that the kids can pull each other with.
  • Dynamics cart and two bricks with small force scale. I have the really old dynamics carts that are big enough to put bricks on.
  • Extra pencils.

RULES! Since no one has protective gear (other than helmets) pucks and sticks must stay on the ice. No slap shots. No “recreational” skating until their assignments are handed in and then I divide the rink in half…. Half for the skaters, half for the non-skaters but still no slap shots. Obviously a stern lecture about behavior and safety is important, with the added penalty of being made to sit out and get zero if they do not follow the rules. I have a series of activities that I request that they do and then they are trying out a few of their own as well. They are required to check their “ideas” with me before trying them out. I get the veto vote. Like, no standing on the skateboard, no using medicine balls as bowling balls… A great exercise in safety and common sense!

Promotion: If you have a com-tech department and they are making promotional videos for the school, or maybe your yearbook department needs some shots, invite them along. Same rules as for the rest of your students. I have a 1-minute video that the com-tech class made for me and there is always at least one good pic in the yearbook.

Assignment/Activities: So what to do? I have attached the assignments that I give my 3U, 4C and 4U classes. A short summary of activities is below. I use this activity as a pre-forces unit investigation for my 3U’s (though I usually give them a list of definitions), a post activity for my 4C and a “review” for my 4U (as they did the 3U the year before). Feel free to add, delete or modify to your heart’s content. I have tried to make the written bits easy to do at the rink and they are done in groups. Some of the stuff is not in their course curriculum but too good to pass up when the opportunity presents itself! To be certain that all of the group members participated in getting the information, you can give a simple T/F observation type quiz the next day and prorate the mark on the assignment accordingly. The assignment can be only diagnostic as well. Also included are my “Not on Ice” assignments for those students not attending. They are geared to my textbook so you will definitely have to modify that. Generally I have very good attendance. The activities are useful for reinforcing concepts as they are encountered throughout the course.

Download the assignments:

Trip day: Don’t forget to give your attendance list to the attendance office in advance. Make arrangements before hand for any students not attending. Make up your groups ahead of time and give the assignments out on the bus. Get the students to help load equipment on the bus, carry it to the rink etc. Remember to have fun! If they see you enjoying yourself, they are more likely to enjoy themselves!

Summary of Activities/Investigations: Here are some of the things we do. The questions about these things are clearly outlined in the assignment files. They can include written discussion, graphing and free body diagrams.
  • Investigating inertia by pushing off on skates or hitting a puck with a stick.
  • Friction: Two people of similar mass, one in skates and one in shoes are pushed by a third person
  • Newton’s Second Law: Push with the same force on two different masses (people, pucks or cart with bricks)
  • Newton’s Third Law:
    • Have two people about the same mass and both wearing skates face each other. They have to have their skates parallel, knees slightly flexed so they are balanced but not digging into the ice. Let person A push on person B.
    • Have a medicine ball and gently throw it horizontally at the second person. They both should move backwards. Make sure the medicine ball is pushed towards the other person’s midriff not thrown at shoulder height!
    • Shoot a puck at the boards. Why does the puck bounce back but the wall does not move?
  • Momentum and Energy: Collisions
    • Two pucks or people with same mass. Hit one puck straight at the second or have the first person skate slowly into the second. Investigate the collision.
    • Tape two pucks together or have two people with different masses. Hit large puck into small and vice versa.
  • Odds and ends:
    • Find someone who can spin in circles on skates. Investigate the changes with arms in or out.
    • Have someone on skates hold a bicycle wheel with handles and spin it. What happens?
    • Go to any door that opens onto the ice. Stand in front of the open door with skate blades parallel to each other but perpendicular to the door. Pull the door toward you, push it away. What happens?
  • Obstacle Course: Choose three students. One in skates, two in shoes. Duct tape sandpaper to the bottom of one of the students’ shoes. Put out your pylons on the blue line. Time each contestant as they pick up the medicine ball and weave through the pylons in a safe manner until they touch the boards. Discuss results.
  • On their own: Have them make up their own investigation. They must explain what they did, what they observed and give their best explanation as to why things happened as they did using the principles they discussed earlier in the assignment. Often they will play with the crazy carpet, the torque wheel, the wheeled cart. They must check in with you if there is some question as to the safety of their experiment before they try it!
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