Objectives 1: To show that a static object (velocity equal to zero) is subject to balanced forces.
One of the common misconceptions: the static position is associated with the absence of forces, while in fact, it corresponds to a balance of equal forces.
Experiments with balanced forces will be performed to demonstrate the presence of forces while a balanced and static position is reached.
What do you think a force is? How do you know a force is present? How do you know forces work on a stationary object? How do you know forces work on you when you are seated in your chair?
Everybody stands up without moving. Ask the question: “did you feel a force on your body ? “
Then jump in the air “What’s happening?”
When the students stands up again, ask them if a force is exerted on their body.
Experiments: A fixed object is always subjected to balanced forces
Ask in each group, to one of the students, to stand up on the scale and to measure the forces. Depending on their age, ask them to write on a piece of paper or to draw the forces on the floor.
Forces are always present even if we don’t always “feel” them. A stationary body is always submitted to balance forces.
Ask students to predict which forces are working on a plane when it stands still on the runway before it starts moving?