Question

The position of a mass on a spring (relative to equilibrium) at time t <= 0 is
x(t) = 2 cos((pi)t) where x is in centimeters and t is in seconds. Answer the ques-
tions. Include units!
(a) What is the initial position of the mass?
(b) What is the initial velocity of the mass?
(c) What is the initial acceleration of the mass?
(d) Does the mass initially move towards the wall or away from it?
(e) At what point does the mass rst turn around?

Answer 1

post the question in physics section Not here @GrizzlyChicken

Answer 2

its in my calc book, isn't this math?

Answer 3

a) put t = 0 and solve for x
b) find x' and put t = 0 and solve for x'
c) find x'' and put y = 0 and solve for x''

Answer 4

it's both physics and math lol

Answer 5

*typo fix* sorry
c) find x'' and put t=0

Answer 6

wait, its x(t)=2cos((pi)(t))

Answer 7

sorry

Answer 8

still~ same way of solving :P

Answer 9

damn, theres another error, i'm gonna look it all over again, for some reason copy and pasting changed everything

Answer 10

at time t is greater or equal to 0. its right now

Answer 11

so if i put 0 for t, its 2cos(0)

Answer 12

yup, that's the initial position

Answer 13

is cos(0)=1?

Answer 14

yes

Answer 15

then for b) derivative of 2 is 0 so its all 0

Answer 16

maybe

Answer 17

no no, find the derivative of the function x

Answer 18

so the derivative of 2cos(pi*0)?

Answer 19

which uses the product rule (0)(cos...)+(2)(-sin(0))

Answer 20

and sin(0)=0

Answer 21

so the velocity is 0

Answer 22

wops sorry i'm here
x = 2 cos (pi t)
x' = -2 pi sin (pi t)

Answer 23

do you know how to derivative?

Answer 24

yea, did you use the chain rule?

Answer 25

is that why pi is with -2?

Answer 26

no chain rule.

derivative of cos is -sin. pi 's brought out when derivative.