Can I Assume Yi is 0m in Projectile Motion Calculations?

  • Thread starter EinsteinApple
  • Start date
In summary, a man is trying to find the distance a water balloon will travel after being launched at 45.0 degrees to the horizontal with a speed of 35.0 m/s from a slingshot he built. Using various equations, including xf=xi + vix t and vfy2 = viy2a + 2ay, the man is able to determine the distance by assuming a launch and landing height of 0 and being consistent with his interpretation of the given quantities.
  • #1
EinsteinApple
10
0

Homework Statement


A man builds a slingshot that can launch water balloons. If he launches a water balloon at 45.0 degrees to the horizontal at a speed of 35.0 m/s, how far away will the balloon hit?

Homework Equations


xf=xi + vix t
vfy=viy+at
yf=yi + 1/2(viy+Vfy)t
yf=yi + viyt + 1/2at^2
vfy2 = viy2a + 2ay

The Attempt at a Solution

:

ti = 0
xi=0
yi = 0 (CAN I ASSUME THIS?)
viy = 24.75 m/s
vix = 24.75 m/s
ax=0m/s2
ay=0m/s2
[/B]
 
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  • #2
As long as you are consistent with the interpretation of the other given quantities, yes you can.
 
  • #3
I just assumed that y2 = 0 because it hits the ground. Therefore, I assumed because he was holding the slingshot y1 couldn't equal 0.
Therefore if y1=0, then y2= a negative value because it's lower.
 
  • #4
Is the balloon launched at some height above ground? What is that height?
When you write
EinsteinApple said:
yf=yi + 1/2(viy+Vfy)t
yi and yf need to be measured from the same point. That's what what I meant by "consistent".
 
  • #5
The problem statement says nothing about the launch or landing height so you have to assume they are the same.
 

1. Can I always assume Yi is 0m?

No, it is not always safe to assume that Yi is 0m. Yi represents the initial position or displacement of an object or particle in a given system, and its value can vary depending on the specific scenario.

2. Why is it important to accurately determine Yi?

Determining the correct initial position of an object is crucial in accurately describing its motion and predicting its future behavior in a system. If Yi is assumed to be 0m when it is not, the calculated results may be significantly different from the actual values.

3. How can Yi be determined in a scientific experiment?

Yi can be determined in a scientific experiment through various methods such as measuring the starting point of an object, using a motion detector, or calculating it based on other known variables and equations.

4. Are there any situations where Yi can be assumed to be 0m?

Yes, there are certain situations where it is appropriate to assume that Yi is 0m. For example, in a simple free fall scenario, if an object is dropped from rest, its initial position can be considered as 0m.

5. How does Yi affect the overall motion of an object?

The value of Yi plays a crucial role in determining the motion of an object. It affects the position, velocity, and acceleration of an object in a given system, and any changes in its value can greatly impact the overall motion of the object.

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