Grade 10 Science - Unit 3 Laboratory 1
Rocket Car
Purpose: To demonstrate Newton's Third Law of Motion with escaping air as
the action force. REALL: Newton’s Third Law states that for every action,
there is an equal an opposite reaction.
Description: Construct a balloon-powered rocket car with the material supplies
that rolls across the floor because air is forced to escape through a plastic
straw.
Materials and Tools that may be
available to build your car
Styrofoam tray
Cellophane tape or duct tape
Cardboard
Metal rods for axels
Push pins
Dowels for axels
Rubber tires
Plastic tires
Flexi-straw
Scissors
Rubber washers
Metal washers
Glue gun and glue
Flexible rubber tubing
String
Drawing compass
Marker pen
Small party balloon
Ruler
Stop watch
Paper or tape for floor
Measuring tape or ruler
Graph paper
Pencil
An Example of Steps to Build a Car and Measure Distance of Travel
1. Using the ruler, marker, and drawing compass, draw a rectangle about 7.5
cm by 18 cm and four circles 7.5 cm in diameter on the flat surface of the
meat tray. Cut out each piece.
2. Inflate the balloon a few times to stretch it. Slip the nozzle over the end of
the flexi-straw nearest the bend. Secure the nozzle to the straw with tape
and seal it tight so that the balloon can be inflated by blowing through the
straw.
3. Tape the straw to the car as shown in the picture.
4. Push one pin into the center of each circle and then into the edge of the
rectangle as shown in the picture. The pins become axles for the wheels.
Do not push the pins in snugly because the wheels have to rotate freely. It
is okay if the wheels wobble.
5. Inflate the balloon and pinch the straw to hold in the air. Set the car on a
smooth surface and release the straw to see if your rocket car works.
6. Using the paper or tape, mark out a straight distance of 10 meters.
7. Mark intervals of one meter on your track.
8. Repeat Step 5 allowing your rocket car to move beside your track.
9. Record the distance traveled for each second and note final time.
10. Repeat the trial runs at least four times, measuring distance and total time
each trial
11. Determine the average distance traveled for all trials.
12. Graph a d-t graph and determine the average speed for each trial.
13. Contrast your data with other teams. What makes one car design perform
better than another? Are large wheels better than small wheels?
Discussion
The rocket car is propelled along the floor according to the principle stated in
Isaac Newton's Third Law of Motion. The escaping air is the action and the
movement of the car in the opposite direction is the reaction. The car's wheels
reduce friction and provide some stability to the car's motion. A well-designed
and constructed car will travel several meters in a straight line across a smooth
floor.
You are encouraged to design your own cars. Cars can be made long or short,
wide or narrow, or even trapezoidal. Wheels can be large or small. If Styrofoam
coffee cups are available, the bottoms can be cut off and used as wheels. Hold
car distance trials on the floor. You will measure and chart the distances each car
travels.
Purpose #2: To demonstrate that the slope of a straight line on a Distance-Time
Graph is Speed
NOTES
Distance (d) = Amount of space between two points
Time (t) = Duration between two events
Speed (v) = Distance traveled over a period of time OR the rate at which
something moves.
= Change in; final value – initial value
t = Change in time (t2 – t1), t1 is often = 0
d = Change in distance (d2 – d1), d1 is often = 0
V= d/ t
= (d2 – d1) / (t2 – t1)
On a Distance-Time Graph, time is the INDEPENDENT variable. Time is
plotted on the x-axis.
Distance is the DEPENDENT variable. It is plotted as on the y-axis
Recall: The equation for a straight line is y = mx + b where
y = dependent variable
x = independent variable
m = slope of the line
b = the y-intercept when x = 0
As noted above, the equation relating distance, speed and time is V = d / t. If
speed and time are known, we need to solve for distance. The formula is
rewritten as d = V t, where
d = distance traveled
V = speed
t = time
If an object has constant speed, we can substitute so that y = mx + b becomes
d = V t + 0 since
d = distance traveled as the dependent variable
V = slope of the line
t = time as the independent variable
0 = initial distance d1 as the y-intercept
Table 1. Results of Trials – November 2008
Trial
Time
Distance
(s)
(m)
1
4
5.5
2
6
6.0
3
6
6.5
4
7
6.0
Speed
(m/s)
Average Distance
Task for Your Laboratory Report
Complete a Materials and Methods sections describing the equipment used to
build your car and the methods used to measure distance traveled
Calculate the speed for each Trial using the data in Table 1
Plot the data on graph paper
Draw an estimated Line of Best Fit through the data. This line should be
straight and it does NOT touch all the data points.
Estimate the Average Speed from the line
In your discussion, present your ideas about the slope of the line representing
speed. You should use the information presented above in NOTES.
DATE DUE: Your completed Laboratory Report on Purpose #2 is due on
Monday, 15 November 2008. NOTE: Include your table of results and
your graph of the data with your report