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DAY 3 OF QUARTER 3
 1)
Welcome Back!
 2)
3 Question Follow Up
 3)
Today: Springs
 4)
Ungraded Activity:
LETS GET READY

HW 1: Look at it, what is not making sense?
TAKE A SPRING, RUBBER BAND AND
POPPER



1 spring per person, but share rubber bands
and poppers
Please note where each one’s ‘equilibrium’ is,
then distort it.
Try to determine:
Which way is the restoring force on each
Why do different springs react differently to the same
pull/push on them?
SPRINGS
 ‘k’
value: Force Constant. How
springy the spring is. Is unique to
each spring.
 Equilibrium:
return to.
 ‘x’
Where spring wants to
value: Distance from equilibrium.
Contains spring energy and has a
restoring force involved.
SPRING IDEAS

Spring (Restoring) Force called Hooks Law:

Spring Potential Energy

At A and –A the restoring force…

At A and –A the energy form is….

At 0…

Our story: Spring-Speed-Height with no E loss.
NOW… GET A POPPER AND A RULER!
In your notes:
Goal: To describe in words
(BUT NOT DO) how to
determine:
The Launch Velocity
The K value of the popper
The force which shot it up
 I expect: a cohesive plan
you can follow that a student
can do with a ruler

SO DO IT!

How would a student do all 3?
Break it down by goals.
QUESTIONS TO PONDER. WRITE THEM,
THEN DISCUSS AND WRITE AN ANSWER.


1) Why did you not need the mass of the popper?
2) How does this situation not violate the
conservation of energy since the system energy
was zero at the start of the entire demonstration?


3) How did the Kinetic energy lost while going up
compare the potential energy gained?
4) While going up, is the system energy
increasing/decreasing/staying the same?
POP IT

Lets draw the transfer of motion for a popper
from when you let go to the top of its pop.
PRACTICE
LET ME TEACH YOU

I will use the fact…