11.2 SPRINGS Flashcards
What does a stretched spring do to object holding each end of spring?
exerts pull on object holding each end of spring
What is the pull exerted by a stretched spring on object holding each end of the spring referred to as?
tension in spring
What is the tension in a stretched spring equal to?
equal + opposite to force needed to stretch spring
What happens to tension the more a spring is stretched?
the more a spring stretched. greater the tension in it
What does Hooke’s law state?
force needed to stretch spring directly proportional to extension of spring from its natural lenght
Equation for Hooke’s law?
force F= kΔL
k- spring constant
ΔL- extension
What happens to a string the greater the spring constant?
the stiffer the spring is
What is the unit for spring constant?
Nm-1
What does F against ΔL show?
straight line of gradient k through origin
What happens if a spring is stretched beyond its elastic limit?
does not regain its initial length when force applied to it is removed
Force needed to stretch P? (springs in parallel: spring P + spring Q) extension ΔL for both springs same
Fp = k p ΔL
k p -spring cosntant of P
Force needed to stretch Q? (springs in parallel: spring P + spring Q) extension ΔL for both springs same
Fq = k q ΔL
k q- spring constant of Q
What is the weight supported by both the springs? (springs in parallel: spring P + spring Q)
W = Fp + Fq = k p ΔL + k q ΔL = k ΔL
What is the effective spring constant? (springs in parallel: spring P + spring Q)
k = k p + k q
What is the extension of spring P? (springs in series: spring P + spring Q) tension in each spring same + equal to weight W
ΔL p = W / k p
k p- spring constant of p
What is the extension of spring Q? (springs in series: spring P + spring Q) tension in each spring same + equal to weight W
ΔL q = W / k q
k q- spring constant of q
What is the equation for the total extension? (springs in series: spring P + spring Q)
ΔL = ΔLp + ΔLq = W/ k p + W / k q = W/k
What is the equation for the effective spring constant? (springs in series: spring P + spring Q)
1/k = 1/k p + 1/k q
What energy is stored in a stretched spring?
elastic potential energy
What happens to the elastic potential energy if a spring is suddenly released?
elastic energy stored in it is suddenly transferred into KE of spring
What is the equation for the work done to stretch a spring by extension ΔL from its unstretched length?
1/2FΔL
F- force needed to stretch spring
What is the work done on a spring stored as?
stored as elastic potential energy
Equation for elastic potential energy stored in stretched spring?
1/2FΔL = 1/2kΔL^2
