Unit 1: Scientific Inquiry/Forces and Motion Newton s Laws Simulation Investigation

Transcription

1 name: period: Learning Objective: Students will understand that the motion of objects depends on the sum of the forces on the object and the mass of the object. Background Information: Complete the following investigation to help you understand how forces change the motion of objects. Part 1: The Problem Bob has been asked to visit a middle school classroom to explain the physics of water slides to some students. Complete the investigation to help Bob collect accurate information about how Newton s Laws of Motion apply to a water park. Part 2: Using Simulations to Model Motion 1. Click this link: and motion basics/latest/forces andmotion basics_en.html or search: phet forces motion basic html The screen should look like this: Part 3: Exploring Net Force 1. Click on Net Force What is net force? Make observations when you conduct the investigation: 1. Place a person on each side of the rope. 2. Hit the go button. 3. Hit the Return button. Try it again with either the same amount of people on each side or a different amount of people on each side.

2 4. Hit the Reset all button. Click box next to sum of forces and values, continue putting men on each side. 5. Hit the Return button. Make the blue team win. What is the net force like? Make the red team win. What is the net force like? Make the teams tie. What is the net force like? Develop an equation for Net (total) Force. Force Net = If the net force is not zero, what is the motion of the object like? If the net force is zero, what is the motion of the object like? Think of one example where Bob would need to calculate the net force on a person at the water park. Written or drawn answer:

3 Part 4: Exploring Motion 1. Click on Motion Make observations when you conduct the investigation: 1. Check the boxes next to force, values, masses, and speed. 2. Change the applied force to 200 N. The screen should look like this: 3. Count to ten, what happens? (Look at the speedometer) 4. Hit reset button. What must be true if the cart continues at the same speed in the same direction? (Think about Law 1). Repeat steps 1 3 with the refrigerator. What happens? (Look at the speedometer). Repeat steps 1 3 using different objects or people and different applied forces. What happens? (Look at the speedometer). What happens to the speed as different objects are added and the applied force is different? How much time does it take for Object Mass Applied Time (Use

4 different objects, with same applied force, get to maximum speed? Maximum speed is reach when the speedometer cannot go any further. (Record your answers in table below.) force (Newtons) 1 crate 2 crates Refrigerator Man Girl Mystery Object stopwatch) To use the stopwatch: screen stopwatch/ Does the object s mass affect the time it takes for the object to reach maximum speed? What do you think the mystery object s mass might be based on how long it took to reach maximum speed at? Think of one example where Bob would need to consider mass and acceleration at the water park. Written or drawn answer: Part 5: Exploring Friction 1. Click on Friction What is friction? Make observations when you conduct the investigation: 1. Check the boxes next to forces, sum of forces, values, masses, and speed. 2. Place the refrigerator on the screen. Change the applied force to 500 N using the arrows. The screen should look like this:

5 3. What happened? Did the refrigerator move? 1. Hit reset button. 2. Check all boxes again. 3. Place the refrigerator on the screen. Change the applied force to 500 N using the arrows. 4. Slide the friction tab toward None. 5. What happens as you slide the friction tab closer to None? 1. Hit reset button. 2. Check all boxes again. 3. Place any object or people on the screen. 4. Change the applied force to 500 N using the arrows. 5. Slide the friction tab toward None or Lots. 6. What happens as you slide the friction tab closer to None or Lots? 1. Calculate the Sum of Forces using the number sentence or equation you came up with on the first page. 2. Complete the table. Fill in the missing values. Click the Sum of Forces box. Did you get the same number using your number sentence or equation? Object Applied Force (N) Friction Force (N) Sum of Forces (N) Crate Man Refrigerator Girl Mystery Object If you did not, how can you revise your number sentence or equation to match the Sum of Forces provided on the screen?

6 How does the force placed on an object affect how it moves? What happens to the motion of the object if there is too much friction? What happens to the motion of the object if only a little friction is added? Where at the water park might Bob need to consider friction? Part 6: Exploring Acceleration 1. Click on Acceleration What is acceleration? Make observations when you conduct the investigation: 1. Check the boxes next to forces, sum of forces, values, masses, speed and acceleration. 2. Place a box on the track. 3. Slide the friction to None. 4. Find a way to make the box accelerate. How do you make the box speed up? Any change in motion is called acceleration. When does the box accelerate? What is the acceleration of each item? Object Mass Acceleration Force (N) (Kg) (m/s/s) Girl Man Bucket

7 Develop an equation for force. Develop an equation for acceleration. Force = x Acceleration = Develop an equation for mass. How much force would Bob need to move the 200kg fridge to the food court if he accelerates the fridge 5m/s2? Mass = Part 7: Communicating Scientifically Develop three important conclusions about motion that Bob should report during his presentation: