Question

A 11-cm-long spring is attached to the ceiling. When a 2.2kg mass is hung from it, the spring stretches to a length of 15cm
a) What is the spring constant k?
b) How long is the spring when a 3.0 kg mass is suspended from it?

Answer 1

F = -kx

Answer 2

do i solve for k?

Answer 3

we can plug in the change in x

Answer 4

F = -k * Delta x

F = -k ( 15 - 11 )

Answer 5

and use weight for force

Answer 6

F = -k * x

m*g = -k * delta x

2.2 * 9.8 = -k ( 15 - 11)

k = 5.39

Answer 7

would the units be Joules?

Answer 8

it says its wrong

Answer 9

oh i think we have to use meters , not cm

Answer 10

SI units

Answer 11

2.2 * 9.8 = -k ( .15 - .11)

2.2 * 9.8 / ( .04) = k

Answer 12

k = 539 , the units are N/m , not joules

Answer 13

how would i solve for b?

Answer 14

so we have
F = -539 * (delta x )
for b) we can plug in the force of weight
3 kg * 9.8 m/s^2 = -539 ( delta x)

delta x = 3 * 9.8 / 539

Answer 15

delta x is .0545 meters
change to centimeters by multiplying by 100

5.45 cm change.
now add that to 11 cm

so the final answer is 16.45 cm