Newton’s Third Law
Area
Sciences
Duration
1 session
Dimension of the advised group of students
One group of 10-20 people
Specific objectives
- To learn about Newton’s laws
- To conduct an experiment
Needed Materials
- Plastic cup
- 2 plastic bendable straws
- String
- Craft knife
- Water and sink
- Modeling clay
If the training is organized online one communication platform will be necessary.
Software
- One online communication platform, such us: Zoom, Google Meet, Webex,
etc.
- In person, no software is needed.
Description
Sir Isaac Newton, a scientist and philosopher of the late 1600’s, spent many years
trying to come up with codified rules that describe how all stuff in the universe
behaves. In the experiment below, we will explore Newton’s third law, which states
that “for every action there is an equal and opposite reaction”—but what does this
mean, exactly?
Imagine dropping a tennis ball to the ground. What happens in response to the action
of the ball striking the ground? It bounces back up towards you. This is due to the
reactionary force of the floor acting against the ball, which pushes it upwards into the
air.
To explore this idea more fully, you can easily construct your very own device called an
aeolipile (sometimes referred to as Hero’s Engine or a Hero engine). Created by an
engineer named Hero of Alexandria about 2000 years ago, this invention was able to
show one way in which an action can lead to an equal and opposite reaction: an
example of Newton's third law.
Participants will conduct their own experiments and be the protagonists of the
workshop. If doing an online training, materials are easy enough to find at home or
could be provided by the organizers.
Procedure on how to put in practice
Duration: 45 minutes
No of participants: 10-20
Methods used: experimentation
Competences developed: research methodology, scientific awareness
Step-by-step description:
1. Ask the group to discuss what they know about the laws of physics. Can they
name any? Introduce Newton and the laws he devised.
2. The experiment is as follows:
a. Take plastic cup poke two small holes near the top rim on opposite sides
from one another.
b. Thread string through the holes and tie a knot so that the cup can be
suspended from the string.
c. Make two slightly larger holes near the bottom of the cup as seen in the
picture below (make sure these holes are just large enough for the straws
to fit through)
d. Cut each straw about 1.5 inches below its bendable portion.
e. Slide the straws into the holes. Make sure that they both point in a
clockwise direction.
f. Use your modeling clay to seal the space between the cup and the straw
so that no water leaks out when you fill the cup.
g. Hold the finished Hero engine away from your body. Pour water into the
cup and observe.
Debriefing question: Where else does this principle apply?
