PhET-Simulations-for-Physics/C3/Projectile-Motion/English-timed
From Script | Spoken-Tutorial
Time | Narration |
00:01 | Welcome to this tutorial on Projectile motion. |
00:05 | In this tutorial, we will demonstrate Projectile Motion PhET simulation. |
00:11 | To follow this tutorial, learner should be familiar with topics in high-school physics. |
00:18 | Here I am using:
Ubuntu Linux OS version 14.04, Java version 1.7, |
00:26 | Firefox Web Browser version 53.02.2. |
00:31 | Using this simulation, we will-
1. Determine how each parameter affects the trajectory of an object. |
00:39 | 2. Estimate where an object will land, given its initial conditions. |
00:45 | 3. Determine how horizontal and vertical motion of a projectile are independent. |
00:51 | 4. Investigate the variables that affect the drag force. |
00:56 | 5. Examine the effect of drag force on the velocity and acceleration. |
01:02 | Let us define a projectile. |
01:05 | A projectile is any object that is fired, pitched or thrown. |
01:11 | The path of the projectile is called its trajectory. |
01:15 | Projectile motion is a form of motion in which a projectile is thrown near the Earth's surface. |
01:22 | A projectile moves along a curved path under the action of gravity. |
01:27 | Gravity is the downward force acting on a projectile. |
01:32 | Gravity influences its vertical motion and causes the parabolic trajectory. |
01:39 | Some examples of projectile motion are- A baseball that has been thrown. |
01:46 | A bullet that is fired from a gun or rifle. |
01:51 | Use the given link to download the simulation. |
01:55 | I have already downloaded Projectile Motion PhET simulation to my Downloads folder. |
02:02 | To open the simulation, right click on projectile-motion_en.html file. |
02:10 | Select the option Open With Firefox Web Browser. |
02:15 | This is the interface of Projectile Motion PhET simulation. |
02:20 | The interface has four screens:
Intro, |
02:25 | Vectors, |
02:27 | Drag , |
02:29 | Lab. |
02:31 | Click on Intro screen. |
02:34 | Using this screen, let's study the factors affecting a projectile’s trajectory. |
02:40 | Intro screen has a cannon mounted on a pedestal. |
02:45 | Default height of the pedestal is 10 m. |
02:49 | Height label disappears when height is adjusted. |
02:53 | We can change the height of the pedestal between 0 to 15 m. |
02:59 | Click on Reset button to reset the simulation. |
03:03 | By default, cannon's angle is at 0 degrees. |
03:08 | Cannon's angle can be changed from minus 90 degrees to 90 degrees(-90 to 90). |
03:14 | Drag Cannon's angle to zero degrees. |
03:18 | At the bottom of the screen, we have: a slider to change Initial Speed, |
03:23 | yellow Eraser icon to erase the trajectory, |
03:27 | red Launch Projectile icon to launch the projectile, |
03:32 | Play/Pause and Step buttons, |
03:36 | Normal and Slow radio-buttons to change animation speed. |
03:41 | At the top left corner, we have Zoom in and Zoom out buttons to zoom the view. |
03:48 | On the top right corner, we have a white box. It contains a probe and a measuring tape. |
03:56 | Probe is used to measure Time, Range and Height of the trajectory. |
04:02 | A drop down list is provided to select the projectiles. |
04:06 | By default, Pumpkin is selected as a projectile. |
04:10 | Mass and Diameter of the selected projectile is displayed below the list. |
04:16 | Next we have a check box to introduce Air Resistance with Drag Coefficient. |
04:22 | Then we have Velocity Vectors and Acceleration Vectors check boxes. |
04:28 | Let us select Human projectile from the list. Observe the displayed Mass and Diameter of the Human projectile. |
04:38 | Click on red Launch icon. Observe the trajectory. |
04:44 | Next we will change cannon's angle to 10 degrees. |
04:49 | Launch the projectile. |
04:54 | Observe projectile's trajectory as we change cannon's angle. |
04:59 | Highest point is shown in green colour. |
05:03 | Drag and place the probe on the highest point of the trajectory. |
05:07 | Note the Time, Range and Height at the highest point. |
05:12 | Let us make tabular column for Cannon's Angle, Time Range and Height. |
05:19 | I will enter the values for 10 degrees angle. |
05:27 | Drag the probe back to its place. |
05:30 | Similarly, I will change the cannon's angle to 20 degrees. |
05:35 | Launch the projectile and observe the trajectory. |
05:40 | Place the probe on highest point of the trajectory. |
05:44 | Note the values of Time, Range and Height in the table.
I have entered the values in the table. |
05:55 | As an assignment:
change the values of cannon's angle and complete the tabular column. |
06:04 | Click on Reset button to reset the simulation. |
06:08 | Launch the projectile and observe the trajectory. |
06:13 | Adjust the target on the base line so that projectile falls on the target. |
06:19 | Launch the projectile and observe the trajectory. |
06:23 | Observe the stars as the projectile hits the target. |
06:27 | By default, slider is at 15 meter per second Initial speed. |
06:33 | Initial Speed can be changed between 0 to 30 meter per second. |
06:39 | Drag the Initial Speed slider to 20 meter per second and launch the projectile. |
06:49 | Notice that projectile moves faster and falls at a greater distance on the base line. |
06:56 | Click on Slow radio-button and launch the projectile. |
07:01 | Observe that the projectile moves slowly. |
07:05 | Notice that Slow radio button slows down the animation speed. |
07:10 | It does not reduce the projectile's speed. |
07:14 | Click on yellow eraser icon to erase the earlier trajectories. |
07:20 | Adjust the cannon's angle to minus 10 degrees and initial speed to 25 meter per second. |
07:28 | Launch the projectile. |
07:34 | Observe the trajectory and distance covered. |
07:38 | Click on Velocity Vector's Total and Components check boxes. |
07:45 | Launch the projectile. |
07:48 | Observe the Velocity vector and its components on the trajectory. |
07:54 | Un-check the boxes. |
07:57 | Click on Acceleration Vectors' Total and Components check boxes. |
08:03 | Launch the projectile and observe the trajectory. |
08:11 | As an assignment, Observe the projectile motion by-
1. Selecting various projectiles 2. Changing initial speed and height of the pedestal. |
08:23 | Next we will move on to Vectors screen. |
08:27 | Click on Vectors screen. |
08:30 | In this screen, we will explore how velocity, acceleration and force are affected by air resistance. |
08:39 | Vectors screen has nearly same tools as in Intro screen. |
08:44 | In this screen, pedestal's height is 0 metres and cannon's angle is 80 degrees. |
08:52 | Change cannon's angle to 70 degrees and launch the projectile. |
09:03 | Here, we have only one projectile - Cannonball. |
09:07 | We can change the diameter and mass by dragging. |
09:14 | Uncheck Air Resistance check-box and launch the projectile. |
09:27 | Without air resistance, projectile moves to a greater altitude and longer distance . |
09:34 | Now click on the following check boxes- Velocity Vectors, |
09:40 | Acceleration Vectors, |
09:42 | Force Vectors. |
09:44 | Launch the projectile. |
09:46 | You will see the vector components on the trajectory. |
09:51 | Next we will move on to Drag screen. |
09:54 | Click on Drag screen at the bottom of the interface. |
09:59 | In this screen, we will- determine the factors that affect the drag force, |
10:05 | observe the relation between drag force and velocity. |
10:10 | Additionally, this screen has Drag Coefficient and Altitude sliders. |
10:16 | Let us move the Drag Coefficient slider to 0.04. |
10:21 | Notice the shape of the projectile. It appears as a water drop. |
10:27 | Launch the projectile and observe the trajectory. |
10:37 | When the drag coefficient is small, projectile travels to a greater altitude and greater distance. |
10:45 | Drag and place the probe on the highest point. |
10:49 | Probe displays the Time, Range and height of the projectile. |
10:54 | Drag the probe back to its place. |
10:57 | Change Initial speed to 14 meter per second and Drag Coefficient to 0.45. |
11:06 | Click Zoom In button to zoom the view. |
11:11 | Launch the projectile and observe the trajectory. |
11:17 | Click on Zoom Out button to show normal view. |
11:21 | Now move the Drag coefficient slider to 0.50. |
11:27 | Change the initial speed to 24 meter per second. |
11:32 | Drag the Altitude slider to 1700 meter and launch the projectile. |
11:45 | Observe the trajectory. |
11:50 | Using measuring tape, measure the distance covered by the projectile. |
12:06 | Now we will move on to Lab screen. |
12:09 | Click on Lab screen. |
12:12 | In this screen, we have a list of projectiles. |
12:16 | Let us select the projectile as Custom. |
12:20 | Here we can change values of Mass, |
12:24 | Diameter, |
12:26 | Gravity, |
12:28 | Altitude and Drag Coefficient manually. |
12:33 | Beside each attribute, notice an yellow coloured edit button. |
12:38 | These buttons are used to change the values manually. |
12:43 | Now I will change Gravity value. |
12:46 | Click on edit button corresponding to Gravity. |
12:50 | A key pad opens. |
12:53 | Select 15 and click Enter. |
12:59 | Check Air Resistance check box. |
13:03 | Change the Altitude value to 2000 meter using edit button. |
13:11 | Launch the projectile and observe the trajectory. |
13:17 | Drag and place the probe to measure the highest point. |
13:22 | As an assignment, change various custom parameter and launch the projectile. |
13:29 | Let us summarize. |
13:31 | In this tutorial, we have demonstrated Projectile Motion PhET simulation . |
13:37 | Using this simulation, we have:
1. Determined how each parameter affects the trajectory of an object |
13:45 | 2. Estimated where an object will land, given its initial conditions. |
13:51 | 3. Determined how horizontal and vertical motion of a projectile are independent. |
13:58 | 4. Investigated the variables that affect the drag force. |
14:03 | 5. Examined the effect of drag force on the velocity and acceleration. |
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