Liberty Science Center 11th
Grade:
What is an equilibrium force?
Grade Level:
11th
Learning Standards:
S1, S16, S5, S6, S7, S8
Time requirements:
Approximately 90
minutes preparation time and 135 minutes class time
Topics Covered
by this Lesson: Vectors and scalar quantities, the resultant of two
vectors, vectors acting in the same direction, vectors acting in any direction,
general method of finding a resultant, the effect of the angle between two
vectors on the resultant and forces in equilibrium
Pre-Visit:
Purpose:
To teach students the important role equilibrium forces play in understanding
the structures of the modern world.
Objectives:
To learn how to represent forces and
motion by vectors. To learn how to obtain the combined effect of two or more vectors
acting upon the same point of a body. To understand how a vector can act in directions other than
its own.
Materials required:
two nails, strings, two spring balances,
a plasterboard, weights of 10N, 15N, and 20N
Students Learning
Prerequisites: Students should know what are vectors, forces, resultants,
mass, weight, the units of measurements used in each quantity. They should also have a basic understanding
of algebra, geometry, and trigonometry.
Visit: Students
will visit the Liberty Science Center and actually get a chance to build structures
like bridges and buildings by using their understanding of equilibrium forces.
Each student will have a chance to design a bridge and building using
materials provided at these exhibits at the center.
Each design will have certain criteria or specifications which students
must adhere to in order for their structure to be physically functioning. For example, the maximum load a bridge
could withstand will be set. The
students will therefore have to compute the resultant force with such a load
and understand the dynamics of equilibrium forces in bridge construction.
Post Visit:
Assessment:
Student’s work will be assessed
in class by using vector diagram to illustrate each example of a successful
or unsuccessful design. Each design will be critiqued by fellow students and the design
voted to be the most structurally sound will be given a prize.
Extensions:
This lesson will be extended into force
and motion, and other vectorial computations.
Homework:
An electric sign is supported by a wire making a 5-degree angle with a boom
as shown in the figure. If the
sign weighs 1000N, what is the outward thrust exerted by the boom? What force is being exerted by the wire
in helping support the sign?
Possible Questions
that may be brought up: