Inclined Plane
Instantaneous versus Average Velocity & Uniformly Accelerated Motion
Wang Zhikai (A0080959N)
Group A1
Pc1221 Lab Report: Inclined Plane
1
Objective
Investigate the relationship between instantaneous and average velocities.
Investigate the relationship between the velocity and distance travelled for a constant
accelerating object.
2
Introduction
The motion of an object can be described by kinematics, and the object’s position, velocity and
acceleration. The average velocity is defined as the rate of change of position in time:
v = (x
f
–
x
i
) / t
, where
v
is the average velocity,
x
f
is the final position of the object,
x
i
is the initial position
of the object and
t
is the change in time interval; the final time minus the initial time. The average
velocity is defined as the rate of change of velocity in time:
a = (v
f
– v
i
) / t
, where a is the average
acceleration,
v
f
is the final velocity,
x
i
is the initial velocity and
t
is the change in time interval; the
final time minus the initial time.
Assuming constant acceleration, we can describe the motion of an object with the following
kinematic equations: 1)
x
f
= x
i
+ v
i
t + ½at
2
2)
v
2
f
= v
2
i
+ 2a ( x
f
– x
i
)
3)
v
f
= v
i
+ at
4)
d = v
i
t +
½at
2
5)
v
2
f = v
2
i + 2ad
The purpose of this experiment is to obtain the different readings produced by measuring the
motion of the object multiple times and using the readings to investigate the relationship between
the instantaneous and average velocities of the object as well as the relationship between velocity
and distance travelled for an object with constant acceleration by using the kinematic equations.
3
Methodology
Part A: Instantaneous versus Average Velocity
1)
Set up a track with the support stand elevated at one end by about 12 cm.
2)
Choose a point x
1
near the center of the track. Note the position of x
1
on the dynamics track
metric scale.
3)
Put a Picket Fence into the slots on top of the dynamics cart with the taped portion facing up.
Use the length of the Picket Fence to represent the length of the cart.
4)
Choose a starting point x
0
for the cart, near the upper end of the track. With a pencil, mark this
spot on the dynamics track so the cart is always released from the same point.
5)
Place the Photogate Timer and Accessory Photogate at points equidistant from x
1
. Record the
distance between the two photogates.
6)
Adjust the height of the photogates so that the Picket Fence can interrupt the photogate
infrared beam.
7)
Set the slide switch on the Photogate Timer to PULSE. In PULSE mode, the Timer measures
the time it takes for the cart to move between the 2 photogates.
8)
Press the reset button.
9)
Hold the cart at x
0
, then release it. Record the time displayed on the Photogate Timer after the
cart has passed through both photogates as t
1
in Data Table 1. Repeat the measurements two
more times, recording the times as t
2
and t
3
.
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 Spring '11
 Tan
 Acceleration, Gate, Velocity, Picket fence

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