Motion in a Plane (Graphing Projectile Motion)

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Homework Help Overview

The discussion revolves around a projectile motion problem involving a baseball hit with an initial velocity at a specific angle. Participants are tasked with determining the velocity and position of the baseball after a set time interval using kinematic equations and trigonometric functions.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants express uncertainty about calculating the vertical and horizontal components of velocity, questioning the use of trigonometric functions (sine and cosine) for this purpose. Some suggest writing separate equations for horizontal and vertical motion, while others emphasize the importance of finding both components.

Discussion Status

Guidance has been offered regarding the need to separate the components of motion and the application of trigonometric functions. Multiple interpretations of the problem setup are being explored, with participants discussing the implications of the angle measurement and the effects of gravity on the projectile.

Contextual Notes

There is a mention of the problem being introductory physics, indicating a potential mismatch in the forum's focus. Participants are encouraged to visualize the problem through diagrams to aid understanding.

unknownplaya
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Homework Statement



Suppose you hit a baseball with an initial velocity of 35m/s at an angle of 52'.

a. Find the direction and magnitude of its velocity 2.5s after you hit the ball.
b. Find the postition vector for the position of the ball 2.5s after it was hit.

Homework Equations



The equations of motion, gravity(-9.81)

The Attempt at a Solution



I'm not sure whether i have to find the vertical velocity component or the horizontal velocity component. I think you have to use sin and cos to find either one but not really sure.
 
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unknownplaya said:

Homework Statement



Suppose you hit a baseball with an initial velocity of 35m/s at an angle of 52'.

a. Find the direction and magnitude of its velocity 2.5s after you hit the ball.
b. Find the postition vector for the position of the ball 2.5s after it was hit.

Homework Equations



The equations of motion, gravity(-9.81)

The Attempt at a Solution



I'm not sure whether i have to find the vertical velocity component or the horizontal velocity component. I think you have to use sin and cos to find either one but not really sure.

Welcome to the PF. In this type of kinematics problem (very common, BTW), you will write two sets of equations. One set of equations is for the horizontal motion, where there is no accelertion assuming no air resistance, so the horizontal component of velocity is constant. In the vertical direction, you have the acceleration of gravity pointing down, creating a force on the projectile. So you use the kinematic equations of motion, with the value of g as the acceleration.

Does that help? Start writing out the equations, and if you have trouble with the trig functions, just consult your textbook or www.wikipedia.org
 
unknownplaya said:

Homework Statement



Suppose you hit a baseball with an initial velocity of 35m/s at an angle of 52'.

a. Find the direction and magnitude of its velocity 2.5s after you hit the ball.
b. Find the postition vector for the position of the ball 2.5s after it was hit.

Homework Equations



The equations of motion, gravity(-9.81)

The Attempt at a Solution



I'm not sure whether i have to find the vertical velocity component or the horizontal velocity component. I think you have to use sin and cos to find either one but not really sure.

I believe you are in the wrong forum for this, this is introductory physics. But...

You need to find both components, vertical and horizontal. You will need to use sine and cosine, but that depends on where the angle is being measured (just remember SOH CAH TOA\rightarrowSine Opposite over Hypotenuse, Cosine Adjacent over Hypotenuse, Tangent Opposite over Adjacent)
 
(Thread moved to Intro Physics)
 
unknownplaya said:

Homework Statement



Suppose you hit a baseball with an initial velocity of 35m/s at an angle of 52'.

a. Find the direction and magnitude of its velocity 2.5s after you hit the ball.
b. Find the postition vector for the position of the ball 2.5s after it was hit.

Homework Equations



The equations of motion, gravity(-9.81)

The Attempt at a Solution



I'm not sure whether i have to find the vertical velocity component or the horizontal velocity component. I think you have to use sin and cos to find either one but not really sure.


you MUST find the components of the velocity... 'cause that's what projectile motions are all about! :)

so it should be:

vertical component = 35sin52
horizontal component = 35cos52

trick: draw out the picture and you'll see why you should use sin and cos. =)
 

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