Insights Blog
-- Browse All Articles --
Physics Articles
Physics Tutorials
Physics Guides
Physics FAQ
Math Articles
Math Tutorials
Math Guides
Math FAQ
Education Articles
Education Guides
Bio/Chem Articles
Technology Guides
Computer Science Tutorials
Forums
Intro Physics Homework Help
Advanced Physics Homework Help
Precalculus Homework Help
Calculus Homework Help
Bio/Chem Homework Help
Engineering Homework Help
Trending
Featured Threads
Log in
Register
What's new
Search
Search
Search titles only
By:
Intro Physics Homework Help
Advanced Physics Homework Help
Precalculus Homework Help
Calculus Homework Help
Bio/Chem Homework Help
Engineering Homework Help
Menu
Log in
Register
Navigation
More options
Contact us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Homework Help
Introductory Physics Homework Help
Initial Speed and Projectile Motion
Reply to thread
Message
[QUOTE="Rubber Ducky, post: 4511817, member: 488727"] [h2]Homework Statement [/h2] So it's a projectile motion problem. I draw a graph showing the parabolic trajectory of the ball, with the start point at the origin. It's final x = 24.8m and final y = 0m [h2]Homework Equations[/h2] We have three constant acceleration equations we use in my course: [tex]\vec{v}_{fx} = \vec{v}_{ix} + \vec{a}_{x}t[/tex] Ensuring everything is in the same direction (vertical or horizontal), final velocity = initial velocity + acceleration * time [tex]\vec{x}_{f} = \vec{x}_{i} + \vec{v}_{ix}t + \frac{1}{2}\vec{a}_{x}t^2[/tex] Looks like an integral. Final position = initial position + initial velocity * time + half acceleration * t squared [tex]\vec{v}_{fx}^2 = \vec{v}_{ix}^2 + 2\vec{a}_{x}Δ\vec{x}[/tex] Final velocity squared = initial velocity squared + double acceleration * displacement [h2]The Attempt at a Solution[/h2] My prof posted a video meant to give hints that will help us get started on the problem. I can try linking it here, though I'm not sure it'll work: [url]https://dal.echo360.com:8443/ess/echo/presentation/7b597979-18b5-413e-8a63-0aca1db8801d[/url] Basically what it says is that, the motion is parabolic, I know the max height, and we know from class that the velocity at a projectile at max height is 0. I then draw a graph with only half the parabola, starting at (x,y) = (0,4.98) and ending at (24.8, 0). Then I have: [tex]\vec{a}_{y} = -9.8m/s/s[/tex] [tex]\vec{v}_{iy} = 0m/s[/tex] [tex]\vec{y}_{i} = 4.98m[/tex] [tex]\vec{x}_{f} = 24.8m[/tex] [tex]t = ?[/tex] [tex]vf = ?[/tex] I use the second equation I listed above to find t: [tex]0m = 4.98m + (0m/s)t + 1/2(-9.8m/s/s)t^2[/tex] [tex]0m = 4.98m - (4.98m/s/s)t^2[/tex] [tex](4.9m/s/s)t^2 = 4.98m[/tex] [tex]t = 1.0081302s[/tex] I keep in mind that this is only the time for half the parabola, so if I use this for the whole thing, I will need to double it. We know from class also that the velocity at the end of a projectile's path is equal to but opposite in direction of the initial velocity. We also know that if we find the x and y components of the final velocity, we can add them to obtain the final velocity. For the y component, I use equation 2 from above: [tex]\vec{v}_{fy} = \vec{v}_{iy} + \vec{a}_{y}t[/tex] [tex]\vec{v}_{fy} = 0m/s + (-9.8m/s/s)(1.0081302s)[/tex] [tex]\vec{v}_{fy} = -9.87968m/s[/tex] For the x component, I use equation 2 (acceleration along x is always 0m/s/s for projectiles, we learned in class): [tex]\vec{x}_{f} = \vec{x}_{i} + \vec{v}_{ix}t + \frac{1}{2}\vec{a}_{x}t^2 [tex]24.8m = 0m + (\vec{v}_{ix})(1.0081302s) + 0[/tex] [tex]24.8m = (1.0081302s)\vec{v}_{ix}[/tex] [tex]\vec{v}_{ix} = 24.599997m/s[/tex] This is where my main problem is. I'm guessing I did all of the above correctly, because it was simply subbing into the equations. I'm just not sure how to get the initial SPEED when I have the VELOCITY components. Hopefully this is easy enough to understand, and thanks for all who read. [/QUOTE]
Insert quotes…
Post reply
Forums
Homework Help
Introductory Physics Homework Help
Initial Speed and Projectile Motion
Back
Top