Finding Acceleration without Time: Help Clarified

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The discussion revolves around finding time when acceleration is known but not explicitly provided, particularly in horizontal projectile motion. The original poster struggles with the equation for change in velocity, leading to an undefined scenario when assuming zero acceleration horizontally. Respondents clarify that in horizontal motion, the initial and final velocities remain constant, allowing the use of vertical motion equations with -9.81 m/s² for acceleration. They emphasize the need to apply both horizontal and vertical motion equations to solve the problem effectively. Understanding the relationship between vertical and horizontal components is crucial for determining time in projectile motion scenarios.
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Homework Statement



Guys, this question is really frustrating me. Ho can I can I Find time when magnitude of acceleration when time is not giving, and also the object is not moving vertically(so I can't use a=9.81m/s?... I tried using (Change in velocity)V= Acceleration* Time,but I eventually get stuck!
Can anyone help Clarify things to me.

Homework Equations


(Change in velocity)V= Acceleration* Time


The Attempt at a Solution

 
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Welcome to PF!

Hi majormuss! Welcome to PF! :wink:

(what exactly is the question? :confused:)

If the projectile starts at an angle to the vertical, then you need two equations, one for the vertical component of motion with a = -9.81 m/s2, and one for the horizontal component with a = 0. :smile:
 


tiny-tim said:
Hi majormuss! Welcome to PF! :wink:

(what exactly is the question? :confused:)

If the projectile starts at an angle to the vertical, then you need two equations, one for the vertical component of motion with a = -9.81 m/s2, and one for the horizontal component with a = 0. :smile:


thnx for the response, but when I assume Acceleration is 0 for horizontal motion my equation ends up... V(f)-V(i)/a... then i get a denominator of 0, which makes it undefined. I can't find time
 


majormuss said:
thnx for the response, but when I assume Acceleration is 0 for horizontal motion my equation ends up... V(f)-V(i)/a... then i get a denominator of 0, which makes it undefined. I can't find time

Well Vf and Vo should be the same for the horizontal because it does not change while in the air (assume no air friction). The previous poster stated there is no acceleration in the horizontal.

In many of these projectile problems, time is usually determined by info. given about motion in the vertical in which case you use your -9.81 m/s/s as your acceleration.
 
majormuss said:
thnx for the response, but when I assume Acceleration is 0 for horizontal motion my equation ends up... V(f)-V(i)/a... then i get a denominator of 0, which makes it undefined. I can't find time

As pgardn :smile: says, Vix and Vfx are the same.

I see now that the problem is that you're only using one of the constant acceleration equations …
majormuss said:
(Change in velocity)V= Acceleration* Time

There are two others! :wink:
 

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