4.18 (page 1) Science Projects For ALL Students Friction Surfaces Is roller blading easier on cement or on linoleum? In this activity you will test different surfaces to see which exerts the most friction. Friction is the force that is caused by 2 surfaces rubbing against each other. Friction helps stop moving objects. A moving object with no friction or other force acting upon it would continue to move forever. All objects, even those that are smooth have bumps and holes on the surface. Friction is caused when the bumps and holes of 2 objects catch each other and stick. Rougher surfaces create more friction than smooth surfaces. friction Words to Know Safety Precautions Please click on the whistle to view the safety guidelines. Make sure no one is walking in the experiment area. Do not use surfaces near traffic. WHAT YOU NEED toy truck (6 inches long or smaller)* 11 x 17 inch cardboard* block 6 inches high Play-Doh tape tape measure WHAT YOU NEED 3 various surfaces (e.g. rug, linoleum, wax paper, aluminum foil, rough sand paper, Plexiglas) the same size magnifying glass Post-its * see Hints 1998 Facts On File, Inc. Published by Facts On File, Inc.
Science Projects For ALL Students 4.18 (page 2) WHAT YOU DO Predict which surface will exert the greatest friction. 1. Set up a ramp using the cardboard and block. Use the Play-Doh to secure the ramp to the block if necessary. 2. Select a surface for testing. 3. Feel the surface and write a description of it in the data table. Is it smooth, bumpy, soft, hard, slick, or rough? 4. Look at the surface with the magnifying glass. Describe it in the data table. 5. Position the surface so that an edge of it is under the lower edge of the ramp. The ramp should hold the surface in place. If necessary, tape the corners of the surface in place. 1998 Facts On File, Inc. Published by Facts On File, Inc.
4.18 (page 3) Science Projects For ALL Students 6. Place the truck at the top of the ramp and release it. 7. Mark the distance from the bottom of the ramp to the point where the truck s front wheels stop with the first Post-It. 8. Measure the distance between the bottom of the ramp and the Post-It. Record the distance in the data table. 9. Repeat steps 5 through 7 two more times. 10. Average the 3 trials. Record the average in the data table. 11. Repeat steps 3 through 10 with your other surfaces. 12. Rank the surfaces in order, from the greatest (1) to the least (3) distance traveled. Record this in the rank column in the data table. OBSERVATIONS 1. What effect did a smooth surface have on the truck s motion? 2. What effect did a rough surface have on the truck s motion? 1998 Facts On File, Inc. Published by Facts On File, Inc.
Science Projects For ALL Students 4.18 (page 4) 3. How could changing the surface of the ramp affect the results of your experiment? 4. How could you increase or decrease the friction of a given surface? Why might you want to do so? 5. Which surface exhibited the greatest friction? Why? OUR FINDINGS Click on the above link to see what we found. 1998 Facts On File, Inc. Published by Facts On File, Inc.
4.18 (page 5) Science Projects For ALL Students Prediction: Surface SURFACES DATA TABLE Description of Surface Distance By Touch Under Microscope Ranking Trial 1 Trial 2 Trial 3 Average 1998 Facts On File, Inc. Published by Facts On File, Inc.
Our Findings 4. PHYSICAL SCIENCES 4.18 FRICTION SURFACES 1. The smoother surfaces took longer to stop the truck. 2. Rough surfaces stopped the truck after a shorter distance. 3. Using a smoother ramp surface would decrease friction. The truck would move off the ramp faster and move further. A rougher ramp surface would exert more force. The truck would move off the ramp more slowly or not move as far. 4. To increase the amount of friction, you would need to roughen the surface. The soles of a new pair of leather shoes are sometimes quite slippery. Scuffing the soles with sand-paper creates irregularities in the surface, creating more friction between it and the floor s surface. To decrease friction you would fill in, or smooth out, any rough spots. For example, we spread oil on metal to fill in microscopic rough spots on the surface. We cook in oil because it stops the food from sticking to the pan. 5. The roughest surface exerts the greatest friction. The irregularities of rough surfaces tend to catch on each other and stick, increasing friction.
Science Projects For ALL Students SAFETY GUIDELINES Special Safety Note To Experimenters Some activities in this book have special safety rules to follow. The special rules are on the page with that activity. But even if every safety rule in the world is included with an experiment, you have to know how to be safe when doing it. So it s very important that you read, copy, and follow the Everyday Safety Rules that follow. Sometimes science experiments can be dangerous. Things can spill, break, or even catch fire. You have to know what to do... fast. So be prepared. Read the directions for each experiment carefully, and follow any special safety rules listed with it, then be careful. Always follow common-sense safety rules like NEVER RUN WITH SCISSORS IN YOUR HAND or BE CAREFUL WITH HOT THINGS! You already know a lot of common-sense safety rules... so remember to follow them, and have fun! Everyday Safety Rules PREPARE Clear off your work space. Read all directions. Know what problems might happen, and be prepared. PROTECT YOURSELF Follow directions step-by-step. Do just one experiment at a time. Locate exits, fire extinguisher, eye wash, and first-aid kit before you start. Ask an adult to show you how to use a fire extinguisher. Be sure there s fresh air in the room. Wear an apron and safety goggles. Don t wear contact lenses, have bare feet, or wear very loose clothing. Keep work space and floor clean. Clean up spills immediately, 1998 Facts On File, Inc. Published by Facts On File, Inc.
Science Projects For ALL Students Don t drink or eat around the experiment work space. Don t eat or drink any stuff tested, unless a grown-up says it s OK. USE EQUIPMENT CAREFULLY Don t set up equipment too near the edge of your work space. Be cautious when using pointed or sharp instruments, like scissors, screwdrivers, or knives. Unplug any electric device by pulling out the plug, not pulling on the cord. Use only low-voltage batteries, like those used in flashlights or smaller. Be careful when using chairs or step-stools. USING CHEMICALS Have an adult help you with all experiments requiring chemicals. Don t inhale or taste chemicals. Read all labels carefully. Label all chemicals. Wear goggles, apron, and gloves so chemicals don t touch your skin. Wash hands before and after using solutions. Wipe up spills thoroughly. HEATING THINGS Wear goggles, apron, and gloves when boiling water. Use safety tongs and heat-resistant mitten or hot pads. Never leave heated things unattended. Turn off hot plates and oven burners when you re finished. Keep flammable things away from heat and flames. Have a fire extinguisher ready. IN THE FIELD Never go on a field trip alone: follow the Buddy System. Tell a responsible grown-up where you re going. Know the area and be aware of dangers, like poisonous plants and deep water Dress for the weather conditions. 1998 Facts On File, Inc. Published by Facts On File, Inc.