How far will a 10 kg block displace a vertically hung spring if the spring’s constant is 70 N/m?
+561 Hooke's Law:
F=kx
F is the force on the spring. Force is the product of mass and acceleration, so it can written as follows.
ma=kx
k is the spring constant, which is given. x is displacement, which is what we're trying to find.
x=ma/k
By subsituting the variables in (9.81 = acceleration due to gravity):
x=10*9.81/70
x=1.40
The spring will stretch 1.4 metres.
+33661 Hooke'slaw says the force required is proportional to the extension, where the proportionality constant is the spring constant. So here (knowing that the force is mass*gravitational acceleration) we have:
10*9.81 = 70*extension
extension = 9.81/7 m ≈ 1.4 m
Thanks but I though hookes law is f= -kx, how do I know when its negative or positive.
+1316 It is negative if you look at the force from the spring. It is positive if you look at the force from gravity.
