Lab Uniformly Accelerated Motion
Acceleration defined as the rate of change of the velocity and the physical quantity quantifying how the
motion of object changes. The average acceleration can expressed as
Uniformly accelerated motion of ar objectis defined as a motion where the acceleration constant Since the
acceleration does not change, the instantaneous acceleration, of the object must be equal the average
acceleration, i.e. the lecture class, we learned that the velocity and displacement of motion
in 1-D given by
where and are the initial position and velocity of the object, respectively ai: the acceleration and is
the time of travel.
In thislab, you will investigate uniformly accelerated motions two different ways, 1) objects in free fall and,
2)the motion an object down an inclined surface As a result, you will find the value the acceleration
due1 gravity on Earth from two different methods and you can compare
Part I Objects ir Free-Fall
Three objects that are safe to drop
Meter stick (or tape measure long ruler etc)
Post- (to anything that can make marks the wall and
Stopwatch (Your cell phone should have one.)
For sufficiently dense objects falling over short distances, we can assume the effects
of drag are small. Thus the motion object free near the Earth's
surface uniformly accelerated motion because, near the surface the Earth, the
acceleration due gravity constant regardless 'an object's mass.
Figure shows an object dropped from rest iie. initial height y above
ground level measured from the bottom of the object. Consider one-dimension
coordinate system set up that the origin ground level (i.e. =0) and the
positive -direction upward, the acceleration the object would a =
Applying equation motion above and remember Vo=0, the position the
object time tisgiven by
y=0 ground level
Soi we measure the time for the object to reach the ground, we can find the value by g : 2yo/t
1. Find three objects of different materials that are safe to drop. For example, you may use ping pong ball,
bouncy ball, golf ball tennis ball, play dough, coins, Lego block, or rubber eraser, etc (Use common
sense! will not responsible anything breaks. Rank them sheavy, medium and light by mass. Enter
the information Tables 1-3 (If you have a suitable scale at home to use. it is even better record
precise masses of the objects.)
Stand by the side wall and precisely measure height of : meters from the floor i.e set yo 2m Use a
Post- anything that you can clean up afterward to mark the height on the wall.
3. Position the bottom (Why? Think! of the heavy object at the 2-meter mark by one hand and hold the
stopwatch on the other hand Drop and time the free fall of the object from the 2-meter mark five times.
Enter the falling time for each drop the appropriate column the Data Tables. Repeat the same
measurements and record the results for the other two objects. Itis important that the person who drops
the object be the same person who does the tirning (Why?) You should Iso practice few times get
consistent results before you start the actual measurements You may also want check the reaction time
4. For each object, calculate the free fall acceleration from each time measurement and find the average
value Find also the percent errors your experimental results (Use g 9.80m/s² as the accepted value
5. Aspartot Results section of your report make sure include the threetables, one for each object and
compare the three calculated experimental accelerations due gravity the accepted value. Include
percent errors these tables. Show your work Note any trends part of the Discussion section make
sure discuss all detectable systernati errors, any, and try suggest ways improve.
Objects different masses were used to investigate whether the acceleration due to gravity depends on
the falling object. Should heavier object faster than lighter one? (Read the textbook
What probably the greatest source of error in this experimental procedure? Is randorn error
Part II: Uniformly Accelerated Motion on the Air Track
1 meter track with built- scale
An object moving ona (near) indined plane has acceleration due to gravity along the length of
The actual air track equipment shownir Figure
is basically smooth metal track with holes drilled on
it and is connected to an air supply. The air car s a
slider that on the track. When the air
Based on the geometry shownir Figure 4 and with some trigonometric function calculations, itis easy to see
that the component the free fall acceleration along the direction of the slopei Soi friction
negligible, the constant acceleration of the the car would be 1= sin6 and the time required travel
distance from resti given the equation:
if the motion applied the car graph the displacement x(t) vs. time we would obtain
parabolic curve. the other hand were graph x(t) time², the graph should straight line
and from the slope the line we able determine the acceleration due gravity. You will verify the
equation above and determine the value of ginthis experiment
Measure one (or more) of the blocks with vernier caliper and place (them) under the back suppor
the track These measurements should be done five times at different positions consure reasonable
Now measure the distance between the supports of the air track along its length These measurement
3. urements frompart the opposite side of a right triangle and part 2isthe hypotenuse of the
triangle. The average values these two measurements then, allow you to determine the sin@ term the
Now, turn on the air source for the air track. NEVER set the air car on the track without the air source
running! Have one member of the group releases from the top ofthe indine and simultaneously
starts the stopwatch Stop the watch when the car has travel led 0.20m down the indine Repeat the time
measu urements for tleast five times and record the results the Data Table.
5. Repeat step for distances of: 0.30, 0.50, 0.60, 0.75, 0.85, 1.00, and 1.25 meters At each distance,
remembert have each lab member do measurement
1. Calculate the average height and the average hypotenuse length 4 the incline Enter your results the
Calculate sin@by using the values from part
3. For each length find the average time travel Then calculate the square of the average time Enter all the
resultsin the Data Table.
Plot the distance travelled (x) vs The graph should exhibit reasonable linear relationship Fit
the data points with straight line and find the slope ofthe fitted line (You should force the intercept
zero the fitting because the origin (O, 0) i an exact point fthe graph.)
5. From the slope of your graph and the value of sin0 determine your experimental value of g
6. Find the percent error between your value of and the accepted value. How consistent were your data
predicting is value?
Should have taken into account the reaction time of each person doing the time measurements? Why
or why not?
Which meas urements do you believe gave us more accurate results, those at the shorter distances or those
the longer distances?
Should we somehow account for the mass the air car our overall analysis? Why or why not?
4. Compare the experimental gir this part to the ones i Part I Which method gives more accurate results?
These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction
of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice.
Unethical use is strictly forbidden.