Ex 1) A force of 12. N stretches a
spring and makes it .15m longer

a) What the spring constant (k) of
this spring?

Ex 1) A force of
12. N stretches a
spring and makes it .15m longer

a) What's the
spring constant (k) of
this spring?

k = F/x

= 12.
N/.15m

= 80.
N/m

b) P.E. of this spring?

PE_{s} = (½)Kx^{2}

= 1/2(80. N/m)(.15
m^{2})

Be sure to use parenthesis when calculating!!

PE_{s} = .90 Joules

Ex 2)
If 15. joules of energy are stored in the stretched
spring below, what is the value of the spring constant?

Ex 2) If 15. joules of energy
are stored in the stretched spring, what is the value of the
spring constant

P.E._{s }
= 1/2(kx^{2})

15. J =
(½)k(.50 m^{2})

1/2 in decimal form is .50

15. J = .50 k(.25)

15 = .125 k

Divide both sides by .125

k = 120 N/m

What's wrong with this picture?

P.E._{s }= (1/2)kx^{2}

x = elongation

P.E._{s }
= 1/2(kx^{2})

PE, X direct square

Plot should be curved

W = DPE

29) A 1200 kg car rolling on a
horizontal surface has a v = 65 km/hr when it strikes a horizontal
coiled spring and is brought to rest in a
distance of 2.2 m.