Name: _______________________________________ Block: ____________ Date: _____________
Resultant Velocity Lab
Mr. White
Conceptual Physics
Re sul tan t Vel o ci ty
Objective:
Students will be able to investigate and experimentally determine the resultant velocity of a motorized toy as
it moves on an incline.
Pre-Lab Reading:
Have you ever walked on a hill? It takes a lot less effort to walk down a hill, than up a hill because factors
other than your muscles are acting on your body. If you have ever tried to walk across a hill sideways, then
you may have realized that it is difficult to actually walk in a straight line.
In this lab, you will be making observations and collecting data for a toy that moves up, down and across a hill.
To determine the motion of any object, a reference point must first be established. By using distance and
time measurements during the motion of the toy, you should be able to determine the resultant speed of the
toy. Your job is to determine how much the “hill” affects the speed of the toy.
To best determine the speed of the toy, a Position-Time graph can be used. The slope of a Position-Time
graph represents the velocity of the toy. The shape of the Position-Time graph can also indicate whether the
toy is accelerating or maintaining a constant velocity. A straight line indicates a constant velocity, while a
curved line indicates an object that is accelerating.
Background Knowledge/Pre-Lab Assessment
1. What does the slope of a Position-Time Graph Represent? ___________________________________
2. What is the resultant velocity of a runner that is moving east at 10 m/s and experiences a head wind of
2 m/s to the west? ____________________________________________________________________
3. How do I determine the resultant velocity of two vectors that are at right angles? _________________
____________________________________________________________________________________
4. Sketch a Position-Time graph that represents an object that is experiencing a positive acceleration.
Position (m)
Time (s)
Name: _______________________________________ Block: ____________ Date: _____________
Resultant Velocity Lab
Mr. White
Materials:
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1 Whiteboard Track
1 Dry Erase Marker
1 Motorized Toy Vehicle
1 Stopwatch
1 Meter Stick
4 Textbooks
Procedure for Data Collection:
Part 1 – Determining the average speed of the Toy.
1. Place the white board track on a level surface.
2. Using the dry erase marker, mark a line at 20 cm from the end of the track and 120 cm from the end of
the track. (See diagram)
20 cm Start
120 m Finish
3. Time how long it takes the toy car to travel from start to finish. Repeat this a total of 5 times. Record
your data in the Data Collection Table.
Part 2 – Determining the velocity of the Toy going down a hill.
1.
2.
3.
4.
Erase the 1.2 m line from the track.
Place Three textbooks under the end of the track that has the starting line.
Turn on the toy and have it run down the hill. Mark the toys position every 2 seconds.
Measure the distance for each dry erase mark from the starting line. Record the data in the Data
Collection Table.
5. Repeat Step 3 and 4, two more times.
Part 3 – Determining the velocity of the Toy going up a hill.
1. Place Three textbooks under the end of the track that is opposite of the starting line.
2. Turn on the toy and have it run up the hill. Mark the toys position every 2 seconds.
3. Measure the distance for each dry erase mark from the starting line. Record the data in the Data
Collection Table.
4. Repeat Step 3 and 4, two more times.
Name: _______________________________________ Block: ____________ Date: _____________
Resultant Velocity Lab
Mr. White
Part 4 – Determining the velocity of the Toy going across a hill.
1. Place 1 test book at the beginning and end of the track, but only place it under one side so that the
track sits at an angle.
Toy
Mark the initial vertical position.
2. Start the toy at the top edge of the hill. Use the dry erase marker to indicate where the toy starts
“vertically.” See diagram.
3. Turn on the toy and have it across the hill. Mark the toys position every 2 seconds. The toy should
move forwards and down the hill at an angle.
4. Measure the distance (d) from the starting line to each mark on the board. Record the data in the Data
Collection Table.
5. Measure how far the toy moved in just the vertical direction (∆Y) for each 2 second time interval. See
the Diagram below.
Toy
∆X
∆X
∆Y
∆X
∆Y
2s
4s
6s
8s
6. Measure how far the toy moving in just the horizontal direction (∆X) for each 2 second time interval.
See the Diagram above.
7. Repeat this experiment 1 more time.
Name: _______________________________________ Block: ____________ Date: _____________
Resultant Velocity Lab
Mr. White
Data Analysis:
Part 1 - Part 1 – Determining the average speed of the Toy.
1. Calculate the average time it took the toy to move 100 cm.
2. Calculate the average velocity of the toy.
______________
______________
Part 2 – Determining the velocity of the toy down the hill.
1. Create a scatter plot Position-Time Graph and a line of best fit to display your data from Part 2.
Position (cm)
Postion - Time
Show work for finding Velocity
220
200
180
160
140
120
100
80
60
40
20
0
0
2
4
6
8
10
Time (s)
2. Use the graph above to determine the velocity of the toy car.
______________
Part 3 – Determining the velocity of the toy up the hill.
1. Create a scatter plot Position-Time Graph and a line of best fit to display your data from Part 2.
Position (cm)
Postion - Time
Show work for finding Velocity
220
200
180
160
140
120
100
80
60
40
20
0
0
2
4
6
8
10
Time (s)
2. Use the graph above to determine the velocity of the toy car.
______________
Name: _______________________________________ Block: ____________ Date: _____________
Resultant Velocity Lab
Mr. White
Part 4: Determining the velocity of the car as it goes across a hill.
1. Calculate the average d, ∆Y and ∆X for all the time intervals.
Time (s)
d
∆Y
∆X
0-2
2–4
4–6
6–8
8 - 10
2. Determine the speed of the train from just the electric motor. Use the ∆X value for each time interval.
3. Determine the speed of the train from just gravity. Use the ∆Y value for each time interval.
Time (s)
Vx
Time (s)
0-2
0-2
2–4
2–4
4–6
4–6
6–8
6–8
8 - 10
8 - 10
Vy
4. Determine the resultant velocity (the actual measured speed when combining gravity and the motor).
Use the d value for each time interval
Time (s)
0-2
2–4
4–6
6–8
8 - 10
Speed (cm/s)
Name: _______________________________________ Block: ____________ Date: _____________
Resultant Velocity Lab
Mr. White
Conclusions:
1. Which of the 4 experiments would be considered the control group?
__________________
2. What is the mathematical difference between the control group and when the toy went up and down
the ramp?
Up the Ramp: _____________
Down the Ramp: _____________
3. Does the difference calculated above represent the resultant velocity of the toy, the velocity of the
electric motor, or the velocity added/subtracted by the ramp?
__________________________________________________________________________________
4. In Part 4, the toy experienced forces that made it move in both the X and Y direction. Draw a diagram
that represents the following vectors: Velocity of Toy Motor, Velocity from Gravity & the Resultant
Velocity for one of the data points from Part 4.
5. Calculate the resultant velocity for each time interval in Part 4. Use the method we learned in class for
adding vectors that are at right angles.
Time (s)
Resultant Velocity
(m/s)
0-2
2–4
4–6
6–8
8 - 10
6. Compare the values from the question above to the data from Question 4 of the DATA ANALYSIS. The
values should be very close (within 2 – 5 cm/s of each other). Do your values match?
____________________________________________________________________________________
7. Even if your values were close, what are some problems that caused your values to not be exact?
____________________________________________________________________________________
____________________________________________________________________________________
Name: _______________________________________ Block: ____________ Date: _____________
Resultant Velocity Lab
Mr. White
Data Collection Tables – Staple to the End of the Lab
Part 1 – Determining the average speed of the Toy.
Trial
Time (s) to move 1 meter.
1
2
3
4
5
Part 2 – Down Hill
Time (s)
Part 3 – Up Hill
Position (cm)
Trial 1
Trial 2
Trial 3
Time (s)
0
0
2
2
4
4
6
6
8
8
10
10
Position (cm)
Trial 1
Trial 2
Trial 3
Part 4 – Determining the velocity of the Toy going across a hill.
Distance from Starting Line (Position) in centimeters
Trial 1
Trial 2
Time (s)
0
2
4
6
8
10
d
∆Y
∆X
d
∆Y
∆X