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

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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