How Do I Solve This Projectile Motion Equation?

  • Thread starter Thread starter chevymechanic
  • Start date Start date
Click For Summary

Homework Help Overview

The discussion revolves around a projectile motion equation involving initial velocity, angle, and time. The original poster presents a specific equation and expresses difficulty in solving for the initial velocity.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the value of the sine function for the given angle and its implications for the equation. Questions arise regarding the interpretation of the sine value and its role in the calculations.

Discussion Status

Some participants provide clarifications about the sine function and its numerical value. There is an indication of progress as the original poster expresses a breakthrough in understanding, although the exact path to the solution remains unclear.

Contextual Notes

The original poster mentions that the equation is an example from a textbook, indicating that they are working through practice problems rather than a specific real-world scenario. There is also a note about ensuring the correct use of degrees in trigonometric calculations.

chevymechanic
Messages
13
Reaction score
0

Homework Statement



Here's the equation I have:

0-730=V0sin(-37.0)(5.00)-(1/2)(9.8m/s2)(5.00)2

Homework Equations





The Attempt at a Solution



I know the answer is 202 m/s. I just can't figure out how to get there. I've reduced it to:

-730=(V0sin(-37.0))(5.00)-122.5

The sine is throwing me a curve ball. It's just an example equation out of the book so that I can solve the real one in my homework. I'm sure it's something simple I'm missing.
 
Physics news on Phys.org
sin(-37.0°) has a real valued result. What is it?
 
Can I ask why is the sin causing you a problem?
 
Why is it confusing you? sin -37.0° is just a number.
 
Last edited:
If you're using a claulator, make sure your trig functions use degrees rather than radians - that might be the trick
 
sin(-37.0)= -.601815

But when I try to solve -730=V0(-.601815)(5.00)-122.5 I get -730=V0-125.509. I just don't see how to go from that to the answer V0=202 m/s
 
chevymechanic said:
sin(-37.0)= -.601815

But when I try to solve -730=V0(-.601815)(5.00)-122.5 I get -730=V0-125.509. I just don't see how to go from that to the answer V0=202 m/s

Vo multiplies (-.601815)(5.00). Don't add (-.601815)(5.00) to -122.5!
 
Haha! Success! I've figured it out. I knew it had to be something simple. I just needed someone to clear things up for me. Thanks a million!
 

Similar threads

  • · Replies 18 ·
Replies
18
Views
7K
Replies
19
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
7K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 12 ·
Replies
12
Views
4K
Replies
40
Views
3K
  • · Replies 14 ·
Replies
14
Views
4K
  • · Replies 3 ·
Replies
3
Views
4K
Replies
5
Views
2K