Projectile Motion Archery Problem

In summary, the conversation discusses a physics problem involving an archery tournament and calculating the speed of an arrow shot from a bow. The problem involves using equations such as v_f = v_i + at and d = v_i * t + 0.5at^2 to solve for the velocity of the arrow. The conversation also mentions the importance of using the correct horizontal and vertical velocity components in the equations.
  • #1
Intex
1
0
Hey guys, i realize this question has been asked on these forums before, and i have seen those posts, but they don't make sense to me, and this question is on my test tomorrow so i really need to figure it out.

Homework Statement



You are watching an archery tournament when you start wondering how fast an arrow is shot from the bow. Remembering your physics, you ask one of the archers to shoot an arrow parallel to the ground. You find the arrow stuck in the ground 61.0 m away, making a 3.00 degree angle with the ground.

So distance in the x direction is going to be 61m
and you have an angle theta that is 3 degrees

Homework Equations



v_f = V_i + at [eq1]
61tan3 = height that the arrow was initially fired from (i think this is where I am wrong)
d = V_i * t + 0.5at^2 [eq2]
Y_f = Y_i + V_iy * t + 0.5 * a_y * t^2 [eq3]
distance = speed*time [eq4]

The Attempt at a Solution



so i got that 61tan3 = 3.197
I used this value in [eq3] as my y_i so i got
0 = 3.197 + 0 + 0.5(-9.8)t^2 and i solved for t which ended up being 0.8077s
then i plugged my time into [eq4] like so 61 = 0.877 * V and got 75.52 m/s for my velocity. But the answer to this problem is 107. What am i doing wrong?
 
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  • #2
The angle is formed by the horizontal and final vertical velocity components not the displacement components.

V_f = V_h tan 3

Where I use V_h for the constant horizontal velocity you wish to find.

You'll need to use eq1 and eq4.

That should be a big enough hint I hope.
 

1. What is projectile motion?

Projectile motion is the motion of an object through the air under the influence of gravity. It follows a curved path known as a parabola.

2. How does projectile motion apply to archery?

In archery, the arrow is launched at an angle, and gravity pulls it down towards the ground. This creates a parabolic path, which is a form of projectile motion.

3. What factors affect projectile motion in archery?

The factors that affect projectile motion in archery include the angle of launch, initial velocity, and air resistance. Other factors such as wind speed and direction can also have an impact.

4. How can the maximum range of a projectile in archery be determined?

The maximum range of a projectile in archery can be determined by finding the angle of launch that allows for the longest horizontal distance. This angle is typically between 35-45 degrees.

5. How does changing the initial velocity affect the trajectory of an arrow in archery?

Changing the initial velocity of an arrow in archery can affect the height and distance of the arrow's trajectory. A higher initial velocity will result in a longer range and a lower initial velocity will result in a shorter range.

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