Let students explore new designs for a pull machine. It does not greatly increase the strength of the movement. The Pull-robot that students are working with uses a bevel gear mechanism to change the direction of the motor rotation. Keep in mind that these tasks extend upon those in the “Investigate” section and are designed for older or more advanced students. Use the “Investigate more” section of the student project as an optional extension. Investigate more (optional, 45-60 minutes) This final step will depend on the friction of the surface the students are working on. Find the heaviest object you can pull with your model when fitted with the tires. This evidence supports the idea that when the pull force is greater than the forces opposing it, objects should move.ģ. The system will suddenly become unbalanced. This will cause the friction among the wheels and the surface to be greater on the Pull-robot side, increasing the force pulling in that direction.

Students will put tires on the Pull-robot. Using the same amount of bricks, put the big tires on the model and test what happens. They will increase the friction on the basket side.Ģ. You can also use the small tires as objects to place in the basket. You can use an arrow to symbolize the direction of the force. At that point, students have balanced forces in front of them. Students can use any object, but each one should not be too heavy, as the goal of this part is to reach equilibrium. (300 g) on a regular surface to stop the Pull-robot from moving. Investigate by adding small objects and then heavy objects to the basket until the device stops moving. Using this model, students should be able to conduct an investigation about pull forces.ġ. Have your students collect their answers with text or pictures in the Documentation tool. Unbalanced forces can cause a change in an object’s motion (speeding up, slowing down, etc.)

Can you infer the relationship among balanced forces and the objects’ ability to move?.This means that at this point, your students’ answers can be incorrect.įollowing the lesson, students should be able to discuss the fact that the motion of the object will be in the direction of the greatest push or pull force. This answer should be based upon students’ predictions in the beginning. Predict what will happen if the pull force is greater in one direction than the other.It is easier to move an object on a slippery surface than on a rough one.ĭepending on the mass of an object, it can also be more difficult to move the object on a slippery surface because there is less grip to push or pull. Can you explain friction? Is it easier to pull something on a normal surface than on a slippery one?.To make it move, pull or push it, or, more generally, apply a force to it. What are some ways you can make an object move?.

Lego wedo 2.0 prevent flooding library