Kinematics

Experiment Title:

What's the notion with motion?

Objective:

Learn about kinematics and Newton's three laws of motion

Background on Kinematics:

Kinematics is a branch of mechanics that describes the motion of objects using words, diagrams, numbers, graphs, and equations. The goal of kinematics is to develop models that serve to describe the motion of real-world objects. The motion of objects has been described over the centuries and can be summed up with Newton’s Laws of Motion.

Newton's first law of motion is often stated as: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Think about when you play with a parachute toy. The parachute will fall towards the ground and would continue to fall if it did not have ground to hit, i.e. it stays in motion until it is stopped by an opposing force, in this case the force is the block of the ground. Or think about when you run a car along the ground. It seems to run along the ground but will slowly stop over time. In this instance there is friction between the tires of the car and the floor. The friction goes against the forward motion of the car. Think about running your car on carpet (has high friction), the car runs along the carpet for a very short time, now run the same car on a wooden floor (has low friction), the car runs along the floor for a very long time but will ultimately stop at some point from the friction.

Newton's second law of motion can be formally stated as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

Newton's third law is: For every action, there is an equal and opposite reaction.

Materials

• Bowl
• Water
• Balls of different weights
• Cardboard
• Fabric
• String
• Balls
• Tape

Method

Prepare/Run Experiment/Analyze Data

• Lab station 1: Demonstration of Newton’s first law of motion - Have a dish of water and have the kids walk a track quickly and see if the water spills at different points and what those points are.

• In general the water spilled when:

• the container was at rest and you attempted to move it
• the container was in motion and you attempted to stop it
• the container was moving in one direction and you attempted to change its direction.

• The water spills whenever the state of motion of the container is changed. The water resisted this change in its own state of motion.

• Lab Station 2: Demonstration of Newton’s Second Law of Motion – Have cardboard ramps and have students test balls of different weights racing down the ramps.

• In general the heavier ball will have more acceleration that the lighter ball.

• Lab Station 3: Demonstration of Newton’s Third Law of Motion - Making parachutes using fabric, paper and string for models

• In general when the parachute pushes against the air, the air pushes against the parachute slowing the speed of fall for the ball attached to the parachute.

Conclusions

Newton's three laws of motion are an important basis for kinematics. Each law can easily be demonstrated by doing simple experiments like the ones in each lab station.

Make It Your Own/Extension Activities to do at home

To make it your own, try using different vessels for the water, is the water's motion different in say a large cup verses a plate? Why do you think that may be? What about using a different size ball that is the same weight as another ball? What happens? Why do you think they reach the end of the ramp at the same time? If you use a different material for the parachute does it act the same as the fabric? What if you use a much heavier material like aluminum foil?