Question

Help please!
A glider is released from rest with a spring stretched 0.100 m. What is the displacement, x, of the glider from its equilibrium position when its speed is 0.20 m/s?

Answer 1

x = 0.1 m
v = 0.2 m/s
do we know what the spring constant is from the the problem?

Answer 2

I believe it is 5.00 N/m

Answer 3

that works for me, so now we know:
x = 0.1 m
v = 0.2 m/s
k = 5 n/m

is there any other information, if not, this is a tough one!

Answer 4

the mass of the glider?

Answer 5

lets see;
m=.200 kg
aannndd I think that is it haha

Answer 6

and that is all we need!
is your class studying kinematic equations, momentum or energy?

Answer 7

umm we just learned conservative energy

Answer 8

ok great, that is what we will use then -

Answer 9

okay :)

Answer 10

sorry, one last question, is the glider being shoot up into the air? or horizontal?

Answer 11

horizontal

Answer 12

so we will break this up in to events
event 1 is when the glider is at rest
event 2 is when the glider is traveling at a speed of .2 m/s

Answer 13

ummm okay

Answer 14

the energy equation will look like this:
KE_spring = KE_spring + KE

event 1 will have the values of
V_1 = 0 m/s
K = 5 n/m
x = .1

can you remember the kinetic energy equations for
KE and KE_spring

Answer 15

oh and event 1 is on the left of the = sign, and event 2 is on the right of the = sign, btw

Answer 16

isn't it 1/2mv^2 ?

Answer 17

or is it 1/2kx^2?

Answer 18

yep, and for a spring its
(1/2) k x^2

Answer 19

if we exchange this equation
KE_spring = KE_spring + KE
for this equation
(1/2) k x^2 = (1/2) k x^2 + (1/2)mv^2
we just now need to plug in what we know from event 1 and event 2
I'll give you a hint,
the x on the left side = 0.1 and we are solving for the x on the right, so we have all the numbers to put in except the x on the right, can you give it a try?

i'll draw a picture so it makes a bit more sense while you work on it

Answer 20

okay thank you! I will see what i get! :)

Answer 21

brb

Answer 22

oh yay i got the right answer! thank you :) so the book says that there are going to be two answers for this problem. one negative and one positive. I don't understand why though?