Student Exploration: Fan Cart Physics
Vocabulary: acceleration, force, friction, mass, newton, Newton’s first law, Newton’s second law, Newton’s third law, velocity Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. Imagine a horse pulling a cart. What would happen to the speed of the cart if several bags of cement were added to the cart?
2.Suppose several more horses were hitched up to the same cart. How would this affect the speed of the cart?
Although these questions may seem simple, they form the basis of Newton’s second law of motion. The Fan Cart Physics Gizmo™ can be used to illustrate all three of Newton’s laws.
The Fan Cart Physics Gizmo™ shows a common teaching tool called a fan cart. Place fan Aon the cart and turn it on by clicking the ON/OFF button below.
1. Look at the blue lines coming from the fan. In which direction is the air pushed?
2.Press Play ( ) and observe the cart. In which direction does the cart move?
3.The velocity (v) of the cart is its speed and direction. Click Reset ( ). Select the BAR CHART tab, and click Play. Does the velocity change or stay the same
Question: What happens to the cart when there is no force?
1. Form hypothesis: What will the motion of the cart be like when there is no force at all?
2.Predict: Suppose a cart with no fans has a starting velocity of 2 m/s. What will be the velocity of the cart when it reaches the wall?
3. Experiment: Check that there are no fans on the cart. On the DESCRIPTION tab, set the Initial velocity of cart to 2.0 m/s. Select the BAR CHART tab, and click Play. What do you notice about the velocity of the cart?
4. Experiment: Click Reset. Place two fans on the cart, and point them in opposite directions. (Next to DIRECTION, click the button for one fan.) Turn both fans on, and click Play. What do you notice about the velocity of the cart
5. Analyze: Select the GRAPH tab. A. What do you notice about the graph of position vs. time (x vs t)?
B. What does the velocity vs. time (v vs t) graph show
C.What do you notice about the graph of acceleration vs. time (a vs t)?
6.Draw conclusions: Newton’s first law states that an object in motion will travel at a constant velocity unless acted upon by an unbalanced force. How do these experiments show this?
Question: How do mass and force affect acceleration? 1. Experiment: Turn on the fans. Click Play and watch the cart, then select the TABLE tab.
A. Scroll to the bottom of the table. What is the final velocity of the cart?
B. How long did it take the cart to reach the end of the track?