8th
~Investigation 6 Force~
In Investigation 6 students are introduced to forces, the ways they interact, and their affects, including friction and accelerated motion.
~Pushes and Pulls A, B, and C~
Students start their inquiry into the concept of force by using a "pusher/puller", made from dowels, rubber bands, and vials. They use this contraption to push and pull things in the room, noting that some objects require more push or pull to put them into motion. A push is equated with force, and force is quantified in terms of the amount of stretch of the rubber band. Students are introduced to the idea that forces add, producing more force or cancelling one another.
~Force and Sleds Lab~
Students use spring scales to measure the force needed to lift a standard mass. They add a friction sled to the system and measure the increased force needed to lift the weight as the sled is loaded with masses. Friction is introduced as a force opposing motion, a force that can be reduced by using rollers under the sled.
~Forces on Carts A and B~
Students will observe demonstrations of force being exerted on one side of a rolling cart and on both sides of the cart. The idea of net force is introduced to explain how force can cause motion in some instances but not in others. Students observe force being exerted on a cart that is positioned against a wall and try to explain why it is not moving. The idea that inanimate objects, like walls, can push is considered. Students use the idea of net force to analyze a number of force problems in parts A and B.
~Force Bench Experiments~
Students will work with the simulated force bench on the computer program Force and Motion to explore force and motion interactions in greater depth. They find solutions to a number of problems on a student sheet. The concepts exercised include force, net force, duration of effort, friction, lack of friction, and acceleration.
