Name:
Date:
Period:
-- Intro to Forces -Lab Simulation
You and some friends are at the park . You find some rope and decide you’d like to play a
game of tug-of-war. Unfortunately, there are 5 people so you can’t have an equal amount
of people on each side. One of your friends suggests that the two biggest people should
be on one side, while the three smaller people should be on the other side. Do you think
this is a fair way to split up teams? Why or why not?
Question: What causes objects to move or stay still?
Open up PhET simulation “Forces and Motion.”
phet.colorado.edu/en/simulation/forces-and-motion-basics
or google “phet forces and motion” and click “Run in HTML5”
TASK 1
a. Place 2 people that are the same size the same distance away from the cart.
b. Make a prediction about the movement of the cart.
c. AFTER you have observed the actual movement, click on the sum of the forces box
at the top right hand corner of the simulation. Record the number in the data chart.
Predicted
Movement
Actual Movement
(none, left, right)
Sum of Forces
(0, x-left, x-right)
Same size, same placement
on rope.
TASK 2
a. Place 2 people that are the same size different distances away from the cart.
b. Make a prediction about the movement of the cart.
c. AFTER you have observed the actual movement, click on the sum of the forces box
at the top right hand corner of the simulation. Record the number in the data chart.
Predicted
Movement
Actual Movement
(none, left, right)
Sum of Forces
(0, x-left, x-right)
Same size, different placement
on rope.
1
TASK 3
a. Place 2 people that are different sizes the same distance away from the cart.
b. Make a prediction about the movement of the cart.
c. AFTER you have observed the actual movement, click on the sum of the forces box at
the top right hand corner. Record the number in the data chart.
Predicted
Movement
Actual Movement
(none, left, right)
Sum of Forces
(0, x-left, x-right)
Different size, same
placement on rope.
TASK 4
a. Place 2 people that are the different sizes different distances away from the cart.
b. Make a prediction about the movement of the cart.
c. AFTER you have observed the actual movement, click on the sum of the forces box at
the top right hand corner of the simulation. Record the number in the data chart.
Predicted Actual Movement
Movement (none, left, right)
Sum of Forces
(0, x-left, x-right)
Different size, different
placement on rope.
On a piece of binder paper, answer these questions:
What causes objects to move or stay still?
Claim:
Evidence:
Analysis Questions/Reasoning:
1. Give an example of a balanced force.
2. Give an example of an unbalanced force.
3. True or false? Balanced forces cause a change in motion. T/F
a. How do you know this?
4. True or False? Unbalanced forces cause a change in motion T/F
a. How do you know this?
Now that you have had a chance to experiment with the simulation, go back to the question at
the beginning of the investigation. What do you think would be the best way to divide up your
friends for the game of tug-of-war? Be sure to explain your reasoning.
Extension/Extra Credit
What questions/investigations do you have after using this simulation?
Devise an experiment of your own using the simulation that helps to answer your question.
2
-- Intro to Forces: Motion and Friction -Lab Simulation
Name:
Date:
Period:
Aim: How does applied force and friction affect the speed of an object?
The science concept is: If Sum of forces are not zero, object speeds up or slows down. If zero
then its speed is constant.
Part I- Motion
1. Click the tab “Motion”
2. Check the boxes next to “ force, values, masses, and speed”
3. Place a box on the skateboard. Pull the slider to 200 in the box. The screen should look like
this:
4. Count to ten, what happens? (Look at the speedometer)
5. Repeat steps 3 and 4 with the refrigerator. (look at the speedometer) Describe the difference
in speed between the crate and the refrigerator.
6. Click the “Reset All” button.
7. Repeat steps 2-4 using different objects and different applied forces. You can also use the
people.
3
8. What happens to the speed, does it slow down as different objects are added and the applied
force is different?
9. Why do you think this happens?
10. Is there a sum of forces?
11. How much time does it take for 1 crate, 2 crates, a refrigerator, the man, the girl, and the
mystery object, with same applied force get to maximum speed? Maximum speed is reached
when the hand on the speedometer cannot go any further. (Record your answers in table
below.) Open a new browser and type in this link to use the stopwatch. http://www.onlinestopwatch.com/full-screen-stopwatch/
Object
Mass
Applied force
(Newtons)
1 crate
300N
2 crates
Refrigerator
300N
300N
Man
300N
Girl
300N
Time (Use
stopwatch)
12. Do you think the object’s mass determines how long it will take for that object to reach
maximum speed with an applied force of 300 N? Yes or No, Explain your answer.
4
Part II-Friction
11. Click the tab “Friction”
12. Check the boxes next to “ forces and speed”
13. Replace the box with the refrigerator on the screen. Click the right Applied Force until it
reaches 500N. The screen should look like this:
6. What happened? Did the refrigerator move?
7. Click the “Reset All” button.
8. Check the boxes next to “values and speed”
9. Place the refrigerator on the screen. Click the right Applied Force until it reaches 500N.
Slowly slide the friction tab toward “None”.
10. What happens as you slide the fiction tab closer to “None”?
Click “Reset All”.
Check the boxes next to “values and speed”
Place any object on the screen. You can also place the people on the screen.
. Click the right Applied Force until it reaches 200N. Slide the friction tab toward “None” or
“Lots”. Stop the friction tab where the friction force arrow is between 100N and 200N.
5. Complete the table. Fill in the missing values.
1.
2.
3.
4.
Object
Crate
Man
Refrigerator
Girl
Garbage Can
Applied Force (N)
200
450
363
500
Friction Force (N)
125
51
100
Sum of Forces (N)
272
99
375
Apply
Now we will call all applied forces positive and all friction forces negative.
Object
Box
Man
Refrigerator
Girl
Garbage Can
Mystery Object
Applied Force (N)
Friction Force (N)
-210
350
-137
200
-50
300
Sum of Forces (N)
190
274
363
122
100
175
1. How does the force placed on an object affect how it moves?
2. What happens if there is too much friction? Will the object move slowly, fast or not at all?
3. What if only a little friction is added, how will the object move?
The END!! Congratulations you are finished.