Sliding friction, rolling friction, and fluid friction



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Average speed is the total distance traveled divided by the total time

Example: If you traveled 100 miles in 2 hours, your average speed would be 50 miles/hr.

  • Constant speed is an unchanging speed. It is neither speeding up nor slowing down. Slope can tell you about the speed of an object. The steeper the slope, the greater the speed.

Example: If you have the “cruise” set in a car, then you are going a constant speed.

  • Instantaneous speed is your speed at any given moment.

Example: If you are speeding up and your speedometer in the car says you are traveling 25 miles per hour, then 25 mi/hr is your instantaneous speed.

Domino Dash (COPY IN JOURNAL)

Problem: to demonstrate the relationship between speed, time and distance.

Background information: Average speed is the rate of motion calculated by dividing the distance traveled by the amount of time it takes to travel that distance.

If you let S stand for the average speed, d stand for distance, and t Stand for time, you can write this equation as follows.



Because average speed is calculated by dividing distance by time, its unit always will be a distance will be a distance unit divided by a time unit.



Materials:

1 box of dominoes stopwatch meter stick calculator



Procedure:

    1. Set up all 28 dominoes with equal spacing between them. Set the dominoes in a straight line to cause a chain reaction when the first domino is pushed.

    2. Measure the length of the domino row. Record this data in the table.

    3. Use the stopwatch to measure the time it takes for the entire row of dominoes to fall after the first domino is pushed. Record the data.

    4. Calculate the speed at which the dominoes fell. Record.

    5. Set up another row of a DIFFERENT length. Repeat steps 3-4.

    6. Repeat for total of 5 different trials.

Speed of Falling Dominoes

Length of domino row (cm)

Time to fall (sec)

Average speed of falling dominoes (cm/sec)














































Data Analysis:

Make a line graph to show the relationship between the length of the domino row and the time it takes to fall. Put the length of the row on the X-axis and the time to fall on the Y-axis.


1. How did we decide what to put on each axis?

2. What relationship do we see between variables? How does the independent variable affect the dependent variable?



Conclusions:

What effect does distance have on the speed of a moving object?

What effect does time have on the speed of a moving object?

Use your notes to fill in the graphic organizer.






Average speed

Constant speed

Instantaneous speed

Description








When used








Which definition of speed (average, constant, or instantaneous speed) did we use in this investigation? Explain why.

What was the independent variable in this experiment? ________________________________

What was the dependent variable in this experiment? __________________________________

What are some controlled variables in this experiment? _____________________________________________________



Why did we use a line graph to explain the data?

Visual Vocabulary-use the following words and definitions to guide your illustrations.

Motion

Is when an object changes its position relative to a reference point.

Distance

Is how far an object has moved.

Displacement

Is the distance and direction from a starting point.

What is Speed?

It is the distance an object travels per unit of time – 60 mph

Rate

any change over time

Formula

Speed = distance / time

Constant Speed

Speed that doesn’t change over time

Average speed

total distance / total time = Avg. Spd = Δ d / Δ t

Instantaneous speed

Speed at a given point in time.

Graphing Distance and Time




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