Projectile Motion Lab Report
(Not a Student’s Design)
Introduction
The experiment was conducted to investigate the independence of horizontal and vertical
components of motion. To predict the landing point of a projectile.
The equation for speed when motion is uniform is v=x/t, where x is distance and t is time
The equation for the vertical distance y in a free fall is y=1/2gt^2. Where g is acceleration of
gravity.
Materials
1. ramp
2. 1/2-inch (or larger) steel ball
3. empty cup
4. meter stick
5. plumb line
6. stopwatch
7. light sources
Procedure
Step 1: Assemble your ramp. Make it as sturdy as possible so the steel balls roll smoothly and
reproducibly, as shown in Figure D. The ramp should not sway or bend. The ball must leave the
table horizontally. Make the horizontal part of the ramp at least 40 cm long. The vertical height of
the ramp should be at least 30 cm.
Step 2: Use a stopwatch or light probe to measure the time it takes the ball to travel, from the
first moment it reaches the level of the tabletop to the time it leaves the tabletop. Divide this time
interval into the horizontal distance on the ramp to find the horizontal speed. Release the ball
from the same point (marked with tape) on the ramp for each of three runs. Record the average
horizontal speed of the three runs.
(See the original for the rest of the steps)
Results
Time B is the time the steel ball took to travel from point O to B and time A is the time the steel
ball took to travel from point O to A.
Horizontal speed is (Horizontal distance)/(Time B- Time A)
Time A
Time B
Horizontal
distance
(distance
between point A
and B)
Horizontal
Speed
Run 1
.93 sec
1.2 sec
0.4 m
1.48 m/s
Run 2
.8 sec
1.18 sec
0.4 m
1.05 m/s
Run 3
.8 sec
1.09 sec
0.4 m
1.3 m/s
The average horizontal speed of the three runs is (1.48 m/s + 1.05 m/s +1.3 m/s)/3, 1.3 m/s.
The height of the vertical distance is 0.915 m. The height of the bottom of the cup does not need
to be taken into account because it is statistically insignificant.
The time it takes the ball to fall from the bottom end of the ramp and land into the cupis 0.432
seconds, because when we use the free fall equation, -0.915m=½(-9.8m/s^2)t^2.
Predicted range R is 0.56 meters because Range = (Horizontal velocity)(Time of the fall),
R=(1.3 m/s)(0.432 s), which is 0.56 m.
Discussion/ Analysis
The actual range of the ball was approximately 0.7m. The percentage error was
20%(|0.56-0.7|\0.7*100%). This is due to the lack of accuracy in timing the time the steel ball
took to travel from point O to B and the time the steel ball took to travel from point O to A. Air
resistance was not a factor because it is negligible.