Physics Lab Exam 2
Hooke's Law
F = -kx Extension is directly proportional to force until the spring reaches it's elastic limit
The force needed to stretch or compress the screen, with spring constant K, and amount of x from equilibrium is
F = kx
The negative sign in hooke's law means
Fs is always opposite to the direction of the stretch or compression (displacement)
By Newtons second law net force is related to the acceleration of the object by
Fx = ma
Area = delta(A) =
Fxdelta(x)
The kinetic energy of an object of mass (m) that moves with a speed (v) is a given by
KE = 1/2mv^2
Kinetic energy is a scalar quantity with units of
Kg*m^2/s^2 = Joule (J)
Work is a scalar quantity that has units of energy of:
N * m = Joule (J)
In hooke's law, when k is a positive constant it's called
Spring or stiffness constant
What is the spring force?
The force exerted by a compressed or stretched spring upon any object that is attached to it
Why can't Kinetic energy have a negative value?
The speed is always squared.
The total work done for the displacement from xi and xf equals to the sum of all delta(W's):
W = (the sum symbol with xf on top and xi on bottom)Fxdelta(x) The area under the force-position is the total work done by the force.
The work, W, done on an object by a constant force, F, is the product of the magnitude of the displacement (delta x) and the component of the force in the direction of the displacement.
W = F delta(x) cos(theta)
The worst done by the spring force doing the stretching from x1 to x2 is
Ws = -1/2(k)(x22-x21)
The total work done by the net force Fx is given by
Wtotal = Fxdelta(x)
The total work done on an object is equal to the change in its kinetic energy
Wtotal = KEf - KEi = delta(KE)
F is for
constant force
The work done by the force to move the object a distance delta(x) can be expressed as:
delta(W) = Fxdelta(x)
What does work represent?
energy transfer from or to the object
If work is transferred from the object, W is
negative
If work is transferred to the object, W is
positive
W is for
work
Fs is a restoring force because it always acts towards
x = 0
