Try this at home!

What crushed this can?

S.M.U. Physics




The can implodes because the atmospheric pressure is greater than the pressure inside the can.

When the can was submerged in the water it caused the water vapor inside the can to rapidly cool.  When a gas is cooled, its pressure goes down. This drop in pressure causes the pressure inside the can to be lower than the atmospheric pressure. 


Note: Use less than 1 cm of water in this experiment (about 1/2 inch)





Elastic P.E. - work stored in a deformed spring

a) General Equation  


PEs = Fx

F = Average Force needed to deform spring

x = distance deformed (stretch or compress)




Noble and Greenough School HS



Ideal Spring

St. Mary's H.S.

Full Screen Version



b)  Hooke's Law - force needed to deform an ideal spring, a given amount is directly proportional to its displacement (deformation)


Graphic from Learning-Connections Clipart


Robert Hooke

'Newton's bitter rival'

Robert Hooke Website


Ex) Ideal Spring


(Force to Deform) (N)
(distance deformed) (m)








Hooke's Law
University of Colorado - PhET



slope = F/x

x = stretch



c) Spring Constant (k), Ideal Spring


- quantifies stiffness of a spring


K = F (N)
X (m)


What is the spring constant of the spring that produced the data? above?


(Force to
(distance deformed)
2.0  .30
4.0  .60
6.0  .90
8.0   1.2

k = 2.0 N
.30 m




k = 6.7 N/m




Which is the stiffer spring?













Spring A is the stiffer spring.

More force is required
for the same stretch





Ex) Plots and K






Pick any point on the line


K = F (N)
X (m)

K = 20. N
.40 m 




K = 50. N/m


31) A spring with k = 53 N/m hangs vertically on a ruler. The end of the spring is next to the 15 cm mark on the ruler.

If a 2.5 kg mass is now attached to the end of the spring, where will the end of the spring line up with the ruler marks?


k = F/x


53 N/m = 2.5kg[9.8m/s2]/x


x  = .46 m + .15 m

ruler reading

=  .61 m



d) Elastic P.E. = area of triangle under F vs x graph




PEs = (½)basexheight


PEs = 6 Joules





Try this at home!



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