Calculating Horizontal Projectile Displacement and Speed

In summary, the problem asks for the magnitude of displacement and speed for a projectile fired horizontally with an initial speed of 50m/s, neglecting air resistance. The calculation for the x component of displacement was done using the equation X=Vox(t)+(1/2)(-9.8m/s^2)(t^2), resulting in a value of 105.9m. However, the y component was initially calculated using an incorrect initial velocity of 50m/s, when it should have been 0m/s since the projectile was fired horizontally. This can be understood through the definition of "horizontally" as having a 0 degree angle above the horizontal. By using trigonometry, it can be seen
  • #1
hakojackie
21
0
The problem states; A projectile is fired horizontally with an initial speed of 50m/s. neglect air resistance. What is the magnitude of the displacement of the projectile 3 seconds after it is fired? What is the speed of the projectil 3 seconds after it is fired? I used this equation to get my X component: X=Vox(t)+(1/2)(-9.8m/s^2)(t^2) and I got 105.9m. I also did this for the Y component I used 50m/s for initial velocity and I think that is what my mistake is, because when I use the pathagorean theorm I don't get the correct answer. Can anyone help?
 
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  • #2
It's fired horizontally, so what is the initial x velocity? What is the original y velocity?
 
  • #3
I got the answer finally the initial velocity for Y is 0m/s. I knew that is where I was going wrong but I still don't really understand why it is 0.
 
  • #4
Because that's what "horizontally" means. If it had any velocity at all in the y direction, either up or down, then it would not be moving horizontal.

It's similar to your other question where it said "60 degrees above the horizontal". "Horizontal" means "0 degrees above the horizontal". You can even do trig on it if you want:

Your other problem:
initial velocity = 30 m/s
x-component = cos(60)*30 = 15 m/s
y-component = sin(60)*30 = 25.98 m/s

This problem
initial velocity = 50 m/s
x-component = cos(0)*50 = 50 m/s, since cos(0)=1
y-component = sin(0)*50 = 0 m/s, since sin(1)=0.

Did you get the right answer? This one was trickier than your last problem.
 

FAQ: Calculating Horizontal Projectile Displacement and Speed

1. What is a horizontal projectile?

A horizontal projectile is an object that is launched or thrown at an angle from a horizontal surface and moves in a curved path due to the force of gravity.

2. How is the horizontal velocity of a projectile calculated?

The horizontal velocity of a projectile can be calculated by multiplying the initial velocity by the cosine of the launch angle.

3. What factors affect the horizontal range of a projectile?

The horizontal range of a projectile is affected by the initial velocity, launch angle, and the force of gravity.

4. Can a horizontal projectile have a negative horizontal range?

No, a horizontal projectile cannot have a negative horizontal range since it always moves in a positive direction due to the force of gravity.

5. How does air resistance affect the motion of a horizontal projectile?

Air resistance can decrease the horizontal velocity and range of a projectile, making it travel a shorter distance and for a shorter amount of time.

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