Fan Cart Physics SE (Disha PDF

Preview

Summary

It is a document contain full solutions to the gizmos. jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj...

Description

Name:

Disha.B

Date:

April 5 2021

Student Exploration: Fan Cart Physics Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. 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? If several bags of cement were added to the cart, the speed of the cart would decrease. 2. Suppose several more horses were hitched up to the same cart. How would this affect the speed of the cart? If several more horses were hitched to the cart, this would affect the speed of the cart because there is more force pulling the positive direction. 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. Gizmo Warm-up The Fan Cart Physics Gizmo shows a common teaching tool called a fan cart. Place fan A on 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? The direction that the air is pushed in is negative. 2. Press Play ( cart move?

) and observe the cart. In which direction does the The direction the cart moves in is positive.

By blowing to the left, the fans exert a force on the cart that pushes it to the right. This illustrates Newton’s third law: A force in one direction results in an equal force in the opposite direction. 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? A change in velocity is called acceleration (a). The velocity of cart A changes, which is called acceleration.

Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

Get the Gizmo ready:

Activity A: Newton’s first law

● Click Reset. ● Remove all fans from the cart.

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? (There is no friction in this model.) I think the motion of the cart to be like when there is no force at all there will be no motion if there is no force. 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? I predict the velocity of the cart when it reaches the wall will be 20 m/s. 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? What I notice about the velocity of the cart is that the velocity is constant 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? What I notice about the velocity of the cart is that it’s velocity is constant. 5. Analyze: Select the GRAPH tab. A. What do you notice about the graph of position vs. time (x vs t)? What I notice about the position vs. time graph is that it is a straight line, which indicates a constant relationship between position and time. B. What does the velocity vs. time (v vs t) graph show? What I notice about velocity vs. time is that it shows us a constant velocity.

C. What do you notice about the graph of acceleration vs. time (a vs t)? What I notice about the graph of acceleration vs. time is the graph shows an acceleration of 0 which means the velocity is not changing. 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?

Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

These experiments show this when the fans act as the unbalanced force. If the fan is blowing in one direction, it will make the cart accelerate and if there are two fans blowing in opposite directions, the cart will remain at a constant velocity because it is a balanced force.

Activity B: Newton’s second law

Get the Gizmo ready: ● Click Reset. ● Set the Initial velocity of the cart to 0.0 m/s. ● Place three fans on the cart, all blowing to the left.

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? The final velocity of the cart is 4.8 m/s. B. How long did it take the cart to reach the end of the track? I took four secs for the cart to reach the end of the track. 2. Calculate: Acceleration is a measure of how much the velocity of the cart changes each second. To calculate acceleration, divide the final velocity by the amount of time it took to reach that velocity. The units of acceleration are meters per second per second, or m/s2. A. What is the acceleration of the cart? (Include units.) The acceleration of the cart is 1.2 m/s2 B. Check your answer on the TABLE tab. Were you correct? Yes I was correct.

3. Form hypothesis: A. How do you think changing the mass of the cart will affect its acceleration? Changing the mass of the cart will affect its acceleration by causing it to accelerate slower than if there was no mass on the cart. B. How do you think the number of fans will affect the cart’s acceleration? Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

I think the number of fans will affect the cart’s acceleration because the cart is causing it to accelerate faster every time a fan is added.

4. Experiment: Select the BAR CHART tab and turn on Show numerical values. For each of the situations below, record the acceleration of the cart. Load

Number of fans turned on

Acceleration

3 fans, 0 blocks

1

0.4 m/s2

3 fans, 0 blocks

2

0.8 m/s2

3 fans, 0 blocks

3

1.2 m/s2

3 fans, 2 blocks

1

0.2 m/s2

3 fans, 2 blocks

2

0.4 m/s2

3 fans, 2 blocks

3

0.6 m/s2

5. Analyze: Look at the acceleration values. A. How did doubling the force affect the acceleration of the cart? Doubling the force affected the acceleration of the cart by having the acceleration double as well, thus making the acceleration double in increase simultaneously as the force is doubling. B. A cart with two blocks and three fans has twice the mass as a cart with just three fans. How did doubling the mass affect the acceleration of the cart? The doubling of the mass affected the acceleration of the car by tripling the acceleration. 6. Collect data: Select the DESCRIPTION tab. On the SIMULATION pane, turn on Show mass. This lists the total mass of the cart. Each fan exerts a force of 4.0 newtons (N). One newton is the force required to accelerate a 1-kg object at a rate of 1 m/s2. For each combination, record the total force, total mass, and acceleration. On the last column, multiply the mass (m) and acceleration (a).

Load

# fans on

Force

Mass

Acceleration

m·a

2 fans, 0 blocks

2

30 N

7.5 kg

1.07 m/s2

8.03 N

1 fan, 2 blocks

1

60 N

15 kg

0.27 m/s2

4.05 N

3 fans, 1 block

3

60 N

15 kg

0.80 m/s2

12 N

What do you notice about the force and the product of mass and acceleration, ma? Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

What I notice about the force and product of the mass and acceleration, ma is that the force acting on an object is equal to the mass of an object times its acceleration. This means the more mass an object has, the more force you need to accelerate it. In addition the greater the force, the greater the object's acceleration. 7. Draw conclusions: Newton’s second law states that force is equal to mass times acceleration: F = ma. This law can be rearranged as a = F / m, or a = F ÷ m. How does this experiment demonstrate Newton’s second law? This experiment demonstrates Newton’s second law of motion because you can use the data tables to work out the equations, so when you try out these rearranged equations you get the same values written in the table chart above.

Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved...