Forces & Motion Classroom Activities

Perhaps the most fundamental aspect of physics is the relationship between an applied force and the motion of an object. Because forces and motion permeate so many levels of physics, they allow a plethora of hands-on activities for students. Students just introduced to the material can benefit from free play with forces and motion, while more advanced students can study applied physics through a computer simulation.

The goal of this activity is to show students that even the slightest forces will affect the motion of objects. An introductory activity, it encourages students to see the physics of motion as they relate to students' own bodies and environment. Students will divide into pairs, each of which has two straws and one rubber ball. They will take turns blowing on the ball, getting a feel for how the ball responds to the force they apply. They should experiment with the amount of force used to begin, slow, stop and redirect the ball's motion. The activity is fairly free-form; no data recording is necessary, but students should write a summary of their experience afterward. The exercise is best suited to students in grades four through six.

This activity complicates the physics of motion by adding the forces of gravity and friction to the mix. Students use stiff cardboard to build a ramp that will form the arena for the exercise. After measuring the ramp's dimensions, they allow a toy dump truck to descend the ramp and record the time it takes for the truck to reach the ground. Then they begin to adjust other variables. Changes to the surface of the cardboard can increase the force of friction between the ramp and the truck. By changing the angle of the ramp, students can affect the force of gravity on the truck. After each adjustment, students should record the corresponding change in the descent time. This activity is for students in sixth through eighth grade.

This activity involves two principles of introductory physics: potential and kinetic energy, as well as Newton's Third Law of Motion, which states that every action provokes an equal and opposite reaction. Students break up into groups, each of which uses a balloon, a straw and a 5-meter length of string. They thread the string through the straw and tape the balloon's neck to the outside of the straw. Students hold the string taught at both ends, and when the inflated balloon is released, they measure how far the balloon-straw assembly traveled along the string. They can use the work equation (work equals force times distance) to measure the force of the balloon's air propulsion.

By blowing up the balloon, students transfer potential energy into the balloon's volume. When the air in the balloon is released as kinetic energy, it exerts a force on the air below it. That air exerts a force of equal magnitude in the opposite direction, propelling the balloon upward. This activity is appropriate for students in grades six through eight.

This Web-based activity requires computers in the classroom. It involves applied physics and is appropriate for high school students. They will visit the Discovery Channel's Earthquake Simulator, which allows them to alter a number of different variables and measure the resulting impact of the quake. The simulator's click-through introduction explains some of the physics involved, particularly the relation between building material and absorption of force. Earthquake physics also involves the relationship between wave motion and force.

Variables the students can adjust in this activity include earthquake force, construction materials and locations of buildings. After each alteration, students should record the effects of the simulated earthquake on their building. It is also important that students provide a written summary of their conclusions.