Science Homework Help

Run this simulation (Links to an external site.) with the settings shown below. Use the Intro Tile. Don’t change any other settings. https://phet.colorado.edu/sims/html/projectile-mot…

To launch the projectile click this button shown

Notice the pause button. You can freeze the motion of the projectile any time you like and as often as you like to develop your answers. Use the measuring tape (just drag it from its location and place it at one location and pull the red + sign to drag it to the other location to measure distance.)

Do Not Turn On Air Resistance.

Initial Post :

What happens when you initially run the simulation?  Does the projectile reach the target? Describe the motion of the projectile. Remember when describing motion we discuss the position, displacement, time, velocity, and acceleration. Between what two points did you measure the horizontal displacement? This measurement is critically important to make accurately. Projectile Motion is a combination of which two types of motion that we have already studied?  Now, make a prediction as to what you need to do to get the projectile to hit the target. Share your original prediction. (Don’t change it because you think it will improve your grade or impress anyone.) Test your prediction. Did you hit your target? Why or why not?  (You are never marked wrong or have a reduced grade for having an incorrect prediction.  It’s common and normal in science to have incorrect predictions when learning. We learn more from these predictions than the ones we are correct with the first time.)

Reply to a Classmate post :    

Reply to a classmate. Provide corrections to anything they may have explained or described incorrectly. If they did everything correctly identify what they did the best and explain why it was particularly good. Did it help your learning? Explain. Include in your reply post an explanation of what happens if you change the mass of the projectile.  For your initial post it was a pumpkin and now change the settings to something else. Try several different masses.  Explain the results.

first reply :

When the simulation is initially ran, the projectile is shot from 10 ft high at 0 degree angle. The projectile is shot straight out for the first 2.0 m while it is still in the cannon. It then proceeds to go downwards out of the cannon until it hits the ground. The projectile lands about 6.42 m past the target, with a total distance of 23.25 m from the 10 foot tall post. The initial speed is at 15 m/s and remains constant through out. The time it takes for the projectile to finish its path is about 1.55 s. This puts its acceleration at 9.7 m/s^2. I measured my horizontal displacement between the initial point and the last point to get 23.25 m. In order for the target to be hit, I believe that the degrees of the cannon would need to be lowered, allowing for the projectile to be shot more towards the ground and spending less time in the air. I also believe that the degrees of the cannon can be kept the same, but the height of the tower that the cannon sits on needs to be significantly lower.

After testing my predictions, I was able to observe that both of my predictions were correct. However, one was more accurate than the other. When the cannon is kept at the initial height of 10 m, but the degrees is lowered to about -15 from 0, the projectile hits the target at the middle white circle. This gives a two star rating. I believe the target was hit because the projectile was given less time to reach the ground when the angle placement was lowered. When the cannon is lowered to 5 m with the same 0 degrees angle, the projectile hits the target dead center, giving three stars. I believe the target was hit because the projectile did not have a high enough placement for it to be shot over the target.I also found that if the initial height and angle were kept, the initial speed needs to be lowered from 15 m/s to 10 or 11 m/s in order to hit the target. I believe the projectile hit the target because it was not forced out of the cannon hard enough to be overshot, and not forced out light enough to be undershot.

second reply :

right when i clicked the launch button the pumpkin flew and landed 6.38 meters away from the target. which was 21.38 meters away frim the cannon. first it started 10 meters high in the air with zero seconds. after 1/2 a seconds the height of the pumpkin was at 8.77 meters. When it hit the ground it took the call ball 1.43 seconds to reach 15 meters. the total displacement was 7.17 meters. the points that I used are 10 meters and 0 meters. the two types of motion are horizontal and vertical motion. I think if I reduce the speed of launch to 10 m/s i could possible hit the target. Yes after launching the pumpkin at a speed of 10 m/s, I successfully hit my target. I hit my target because I thought since the cannon us at a height of 10 meters and the target is 15 meters away, maybe I could match the height and go at at he same speed. Since 15 m/s was too fast which made it go farther, 10 m/s was better and reached the target.