PhET-Simulations-for-Physics/C3/Projectile-Motion/English-timed

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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.
14:09 The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it.

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14:52 This is Madhuri Ganapathi from IIT Bombay, singing off.

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