# spring force

• Mar 3rd 2009, 07:42 PM
lirjie
spring force
a. if it takes a force of 100N to compress a certain spring a distance of 5 cm, how much force would be required to compress the same spring by 10cm?

b.how much force would be required to compress by 5 cm a spring with twice the spring constant as the spring in part (a)?
• Mar 3rd 2009, 07:48 PM
mr fantastic
Quote:

Originally Posted by lirjie
a. if it takes a force of 100N to compress a certain spring a distance of 5 cm, how much force would be required to compress the same spring by 10cm?

b.how much force would be required to compress by 5 cm a spring with twice the spring constant as the spring in part (a)?

F = kx where x is the change in length.

(a) 100 = 5k => k = 20 N/cm. Therefore F = (20)(10) = 200 N.

You should be able to do (b) now.
• Mar 3rd 2009, 08:05 PM
lirjie
thank you!! i understand part a, i actually had the same answer u got but its part b that im having the most difficulty with..would this be right

f = -kx

200N = -k5
k= 40N

?????????
• Mar 3rd 2009, 08:13 PM
mr fantastic
Quote:

Originally Posted by lirjie
a. if it takes a force of 100N to compress a certain spring a distance of 5 cm, how much force would be required to compress the same spring by 10cm?

b.how much force would be required to compress by 5 cm a spring with twice the spring constant as the spring in part (a)?

Quote:

Originally Posted by lirjie
thank you!! i understand part a, i actually had the same answer u got but its part b that im having the most difficulty with..would this be right

f = -kx

200N = -k5
k= 40N

?????????

k = 2(20) = 40 N/cm. Therefore F = (40)(5) = 200 N.
• Mar 3rd 2009, 08:27 PM
lirjie
thank you so much!!!!

i dont understand however where you got 2 and 20 from...(2)(20)= 40???
• Mar 3rd 2009, 08:32 PM
mr fantastic
Quote:

Originally Posted by lirjie
thank you so much!!!!

i dont understand however where you got 2 and 20 from...(2)(20)= 40???

*Ahem* ...... twice the spring constant as the spring in part (a)