Understanding Projectile Motion: Question on Angle and Distance

  • Thread starter psmarz
  • Start date
  • Tags
    Projectile
In summary, the ball is thrown with the same speed at an angel of 35 deg upward. It travels 20.5 m/s.
  • #1
psmarz
32
0

Homework Statement


The ball is now thrown with the same speed at an angel of 35 deg upward. How far does it travel?

My question is...

They have

vhor = (25 m/s) cos 35 deg = 20.5 m/s

and

The angel with the vertical is (90 - 35) = 55 deg
so...

vvert = (25 m/s) cos 55 deg = 14.3

It seems backwards to me for some reason because it says that the ball was thrown at a angel of 35 deg upward.

Can someone help me understand why 35 deg is tacked onto the horizontal while 55 is tacked onto the vertical?
 
Physics news on Phys.org
  • #2
Usually when talking about projectile motion the angel is to the horizontal line. So you aim 35 degrees up from the horizon. And if you take a closer look at the geometry of a triangle you'll see it is possible to use the same angel for horizontal and vertical speed. Just keep in mind that you can move vectors around.
 
  • #3
Kruum said:
Usually when talking about projectile motion the angel is to the horizontal line. So you aim 35 degrees up from the horizon. And if you take a closer look at the geometry of a triangle you'll see it is possible to use the same angel for horizontal and vertical speed. Just keep in mind that you can move vectors around.

Ok I do not get how the angel with the horizontal is 35 while the vertical is 55 because you aimed 35 degree upward.
 
  • #4
I hastely put together a picture of the situation.
http://www.aijaa.com/img/b/00677/3628783.jpg [Broken]
a is the vertical speed, b is horizontal speed and c is a and b combined. Those two pictures mean the exact same thing, I've just moved a. How would you solve a from the picture on the right, if you only knew the value of c and the angel?
 
Last edited by a moderator:
  • #5
Thank you for the visual. I am new to the whole SOH, CAH, TOA and that visual helps greatly...

C = 25m/s
B = 20.5m/s
A = 14.3
 
  • #6
psmarz said:
C = 25m/s
B = 20.5m/s
A = 14.3

So did you find out, why you can also use 35 degrees instead of 55? Can you show me how you got those figures?
 
  • #7
(35 sin) 25 = 14.3

They did it by subtracting 35 from 90 and doing (55 cos)25 = 14.3
 
  • #8
psmarz said:
(35 sin) 25 = 14.3

They did it by subtracting 35 from 90 and doing (55 cos)25 = 14.3

Yep!
 
  • #9
Thank you for helping me figure it out.
 
  • #10
psmarz said:
Thank you for helping me figure it out.

You're very welcome!
 

1. What is a projectile?

A projectile is any object that is launched into the air and moves along a curved path under the influence of gravity.

2. How is the trajectory of a projectile determined?

The trajectory of a projectile is determined by its initial velocity, launch angle, and the force of gravity acting on it.

3. What factors affect the range of a projectile?

The range of a projectile is affected by its initial velocity, launch angle, air resistance, and the height at which it is launched.

4. How does air resistance impact the motion of a projectile?

Air resistance can slow down the motion of a projectile, causing it to have a shorter range and a lower maximum height.

5. What is the maximum height reached by a projectile?

The maximum height reached by a projectile is determined by its initial velocity, launch angle, and the force of gravity acting on it. It will reach its maximum height at the highest point of its trajectory.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
811
  • Introductory Physics Homework Help
Replies
2
Views
766
  • Introductory Physics Homework Help
Replies
8
Views
1K
  • Introductory Physics Homework Help
Replies
25
Views
2K
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
1K
Back
Top