This preview shows pages 1–2. Sign up to view the full content.
Physics 123  Minilab 7
WORK AND KINETIC ENERGY
Introduction
Work is done by a force acting over a distance.
According to the workkinetic energy theorem,
the kinetic energy
K
of an object will change by the amount of work W done on the object. With
a constant force
F
acting parallel to a displacement
d,
we have:
∆
K = W = Fd.
(1)
We will measure the change in kinetic energy of a cart rolling down an inclined track.
The
force due to gravity on the cart
along the direction of motion
depends on the mass of the cart
and the angle
θ
of the track to the horizontal:
F
1
= F
g
sin
θ
= mg sin
.
(2)
Of course, the cart’s wheels are not free of friction, and if we assume that the frictional force
f
k
is constant, then the total force acting on the cart is
F = F
1
– f
k
(3)
and thus
K = (F
1
– f
k
)d.
(4)
Procedure
1.
Set the track at an angle of about 5 degrees using the wood. Determine this
angle by measuring the elevation h of the track at two positions x; record these
data on the next page. Calculate the angle and record it, along with the mass of
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Fall '08
 Madey
 Physics, Energy, Force, Kinetic Energy, Work

Click to edit the document details