TESSA Secondary
Resource 4
Teacher resource for planning or adapting to use with pupils
Examples of physics in action
Places to visit and examples you might see
Place
Examples
Physics principles they use
Garage or
workshop
Hydraulic jacks
Pressure = force/area
and pressure is transmitted through a fluid (oil), so
input pressure = output pressure
Used as a ‘force multiplier’
Brace, screwdriver
Input force x input distance from axle =
output force x output distance
A force multiplier
Building site
Pulleys
Input force x distance it moves =
output load raised x height it is lifted.
A force multiplier
Wheelbarrows and
levers
Input force x input distance from wheel axle or pivot =
output force x output distance from pivot
A force multiplier
Kitchen or
bakery
Can openers,
potato chippers,
nut-cracker
Examples of levers as force multipliers, so small force
exerted by operator on the handle produces a large
force on the object:
Input force x input distance from pivot =
output force x output distance
Playground
Knives and
skewers
Narrow blade edges and fine points cut into the
material more easily because, for the same force,
reducing the area increases the pressure
Seesaw
Another lever example: a lighter person sits further out
to balance a heavier person.
Clockwise moment = anticlockwise moment
Farm/garden
Shears/secateurs/
branch cutters
Force multipliers:
Input force x input distance from pivot =
output force x output distance
TESSA Secondary
Some examples of force multipliers
Hydraulic jack:
You use a small force but push further to raise the large load a smaller distance.
Input pressure = output pressure
because the pressure is transmitted by oil.
•
narrow input piston cylinder with area A1 , small input force F1
•
wider output piston cylinder with area A 2 , larger output force F 2
•
force on output piston
Force on input piston Force exerted by output piston F2 F2
=
=
A1 A2
Area of input piston
Area of output piston
Levers , e.g. see-saw:
Clockwise turning force x distance from pivot =
anticlockwise turning force x distance from pivot
Distance of person A from pivot Weight of person B
=
Distance of person B from pivot Weight of person A
Cutting tools e.g. secateurs, shears: