PH1004 laboratory Instructions
Exp 1: One Dimensional Motion
1
PH 1004 Laboratory Instructions
Experiment 1
One Dimensional Motion
Background
The
displacement
of an object is defined as change in its position.
In this
experiment you will investigate objects traveling along a straight line, that is, you will
deal with onedimensional motion. We will assume therefore that an object is constrained
to move along the xaxis.
To determine the displacement along the xaxis, one needs to subtract the object’s
initial position
x
i
from its final position
x
f
.
That is,
i
f
fi
x
x
x
−
=
,
(11)
where
x
fi
is the displacement of the object.
The unit of displacement is meter [m] in the
SI system.
The
average velocity
is defined as the total displacement divided by the time
elapsed during the displacement.
If the object is at position
x
i
at time instant
t
i
, and at
position
x
f
at time instant
t
f
, its average velocity in the xdirection is defined as
,
i
f
i
f
fi
fi
av
t
t
x
x
t
x
v
−
−
=
=
(12)
where
t
fi
=
t
f
–
t
i
is the elapsed time.
The unit of velocity is meter per second [m/s] or
[ms
1
] in SI system.
The
instantaneous velocity
is defined as:
dt
dx
t
x
v
fi
fi
t
fi
=
=
→
0
lim
.
(13)
This is the derivative of position of the object with respect to time.
Since it is not
possible to measure infinitesimally small quantities, we approximate the value of
v
by
dividing a sufficiently small distance interval
x
fi
by the corresponding time interval
t
fi
.
That is,
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
PH1004 laboratory Instructions
Exp 1: One Dimensional Motion
2
fi
fi
t
x
v
≅
,
(14)
where
t
fi
is made as small as possible in the experiment.
In similar fashion, the
average acceleration
is equal to the difference in
instantaneous velocity divided by the difference in time:
i
f
i
f
av
t
t
v
v
a
−
−
=
(15)
The
instantaneous acceleration
in the xdirection is defined as the limit of
average acceleration defined by formula (15) as
t
fi
approaches zero, which is the
derivative of the instantaneous velocity with respect to the time.
That is,
dt
dv
a
=
.
(16)
The unit of acceleration is [m/s
2
] or [ms
2
] in the SI system.
Apparatus
Air Track
In this experiment you will use an air track to investigate onedimensional motion
along a straight line.
To proceed with the experiment, it is important to understand how
the air track works. A photograph of the air track apparatus which is used in experiments
#1, 2 and 3 of this course is presented in Figure 11.
The air supply pressurizes the air
inside the air track. Tiny holes on the air track surface allow thin streams of air to
emerge. These thin streams push symmetrically on both fins of the glider, creating a thin
air gap between the glider and the air track surface, as shown in Figure 12.
Before any experiments can be run on the air track, it must be carefully
leveled.
A tilted track will cause the glider to slide in one direction or the other.
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 WORMER
 Physics, Acceleration, Velocity, TFI

Click to edit the document details