This can be done in 4th grade too!
Students will use the concepts of force and motion to create a paper roller coaster. They will have the opportunity to calculate speed of various types of marbles. They will also be exposed to the idea of velocity.
|Recommended Grade||5th grade|
|Sciece Topic||Force and Motion|
NC Science Standards
Two forces commonly at work are gravity and friction. Gravity is the force that pulls somethings toward the Earth. Friction is a force that happens when two things rub together, friction is a force that works against motion.
Gravity is constantly pulling us toward the center of the earth. Whatever else is going on, Earth gravity is always pulling them down. If you are sitting on a chair gravity is pulling you toward the earth and the chair is pushing you up, balancing the force of gravity. Since the forces are balanced, your motion doesn’t change. You just sit there. But if the chair is yanked away, you will fall to the ground because there is no more force pushing you up. The force of gravity is unbalanced and you fall down to the ground because when forces are unbalanced things happen.
Friction happens whenever two objects are touching – or are in contact – with each other and one moves against the other. It creates a force that is opposite to the direction of the motion. When a ball is rolling, friction acts opposite to its roll. If there are no other forces to keep it going, the unbalanced friction stops the ball.
All of this talk about how something keeps doing what it was doing when the forces acting on it are balanced is called Newton’s first law of motion. It describes inertia. Inertia is the tendency of something to resist changing its motion. The more inertia something has, the harder it is to change its motion.
It turns out that the inertia of something is the same as its mass, or how much of it there is. Mass refers to the amount of stuff packed into something. More massive things really want to keep doing whatever they were doing, they oppose changes in their motion.
Roller Coaster Math
Let’s learn to calculate speed! Speed is simply how fast something is going, it’s a rate of change. A rate measures how much of something happens over time. Speed is how much position changes, that is, the distance something moves in a certain amount of time. For example, car speeds are given in miles per hour. If a car is traveling 50 miles per hour this means it will move 50 miles in one hour.
What information do we need to calculate speed? We need distance and time. Distance and time can be measured. We can measure shorter distances with a ruler and longer distances can be found on a map. We can measure time with a watch or a stopwatch depending on the time interval. Shorter time intervals such as seconds may be difficult to measure on a traditional watch, so for short intervals we use a stopwatch. Longer intervals, such as minutes or hours, can be measured with a regular watch.
speed (s) = distance (d)/time (t)
Calculate the average speed of a marble traveling through a paper rollercoaster given a track length of 60 inches and a time interval of 30 seconds. What is the average speed of the marble?
s = d/t s = 60 inches/ 30 seconds s = 2 inches per second
We want to give our answers as velocity not speed. I know you thought speed and velocity were the same thing! Velocity is a term that has a magnitude and a direction. So velocity is simply the speed with a direction given. If a car travels from Florida to Maine at 50 miles per hour, the speed is 50 miles per hour but the velocity is 50 miles per hour north.
In our example calculation the average velocity is 2 inches per second, downward
If something’s in motion it has momentum. If something’s not in motion, in other words at rest, it has no momentum. Momentum is related to the mass and velocity of an object, specifically momentum is equal to the mass of an object times it velocity. So objects with greater mass have greater momentum, objects with greater velocity also has greater momentum. Objects with greater mass and greater velocity have even more momentum. In each of these cases we are multiplying larger numbers to get the momentum. Remember objects in motion have directions associated with them, like velocity momentum has a magnitude and a direction. The direction of momentum is the same as the velocity. Using the velocity and the mass of an object we can calculate its momentum:
momentum (p) = mass (m) x velocity (v)
Paper Roller coaster Project Example Problem:
Going back to our average speed problem lets now calculate the momentum of our marble. We know the velocity is 2 inches per second downward and we measure the mass to be 12 grams.
We simply carry the units along with the multiplication so we multiply grams by inches per second which gives us gram inches per second.
1. Students will practice patience.
Video link coming soon
Time Estimation:45-60 minutes for 3-5 days
The 2016-2017 school year will be our first year with 5th grade students. We are excited to incorporate the math piece into this project with our 5th graders. It is not necessary to include the math in this project.