Finding time up and time down: Verticle Projectile

In summary, the conversation discusses a problem involving a vertical projectile launcher and finding the time it takes for the projectile to fall back to the top of the launcher. The known variables are the distance from the top of the launcher to the top of the ball's flight, the distance of the compressed spring, and the mass of the ball. The speaker initially calculates the time using a formula, but the professor marks it wrong. They then discuss other possible ways to calculate the time, including using the initial and final velocities. The conversation ends with the possibility of the professor marking the answer wrong by accident.
  • #1
Mirth
23
0
[SOLVED] Finding time up and time down: Verticle Projectile

Hey guys, so I have a take home lab that is just murdering me...

Imagine a vertical projectile launcher that sits on the ground, that shoots a ball up in the air and lands back in the projectile.

The knowns are:
distance from the top of the projectile launcher to the top of the ball's flight = 0.5m
distance of the compressed spring = .033m
and mass of ball = .00965kg

Now, I thought time down could be gotten using Sqrt(2 * d/ g), which would be Sqrt(2 * .5m/9.8) = .319 seconds, but the professor marked that wrong.

Other than that, I know that V_i = 0 when the ball is at the top of it's flight. So I decided to get V_f by using V_f = Sqrt(2 * g * d), which is Sqrt(2 * 9.8 * .5m) = 3.13 seconds. But I don't know how I can get time down using those two.

Also, I "figure" time down would be the same as time up. With that said, if the initial velocity is 3.13m/s and the final velocity is 0m/s for the time up, then V_f - V_i / g
= 0 - 3.13 / 9.8 = 3.19s . That's what I got for my time down on my paper, so if time up is = to time down, and I got my time down marked wrong when it was .319, then both aren't .319 :(

Edit: Err, but then wouldn't the force of the spring be a factor? I'm so confused...
 
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  • #2
Are you trying to find the time it takes the projectile to fall back down to the top of the launcher or are you trying to find the time it takes to fall back to the foor?

How high is this launcher? If it is significantly high, the time it time it takes to hit the floor may be significantly longer.
 
  • #3
G01 said:
Are you trying to find the time it takes the projectile to fall back down to the top of the launcher or are you trying to find the time it takes to fall back to the foor?

How high is this launcher? If it is significantly high, the time it time it takes to hit the floor may be significantly longer.

Fall back to the top of the launcher, not the floor, yup.

Someone sort of helped me for the time down, and he also got .319s, so I think my professor may have marked it wrong by accident...
 
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  • #4
Mirth said:
Fall back to the top of the launcher, not the floor, yup.

Someone sort of helped me for the time down, and he also got .319s, so I think my professor may have marked it wrong by accident...

Quite possible. Professors are human too, despite evidence suggesting otherwise:smile:
 

1. What is a vertical projectile?

A vertical projectile is an object that is launched into the air at an angle with respect to the ground.

2. What is the significance of finding time up and time down for a vertical projectile?

Finding time up and time down for a vertical projectile allows us to calculate the total time the object spends in the air and its maximum height, which are important factors in understanding the motion of the object.

3. How do you find the time up and time down for a vertical projectile?

To find time up and time down for a vertical projectile, we use the equations of motion and the initial velocity and angle of the object. Time up is calculated using the equation t = 2v*sinθ/g, and time down is calculated using the equation t = 2v*cosθ/g, where v is the initial velocity, θ is the launch angle, and g is the acceleration due to gravity.

4. What factors can affect the time up and time down of a vertical projectile?

The time up and time down of a vertical projectile can be affected by the initial velocity, angle of launch, air resistance, and the gravitational force of the Earth.

5. How is the time up and time down of a vertical projectile used in real-life applications?

The understanding of time up and time down for a vertical projectile is important in various fields such as sports, engineering, and ballistics. It is used to predict the trajectory of projectiles, design efficient structures, and improve the performance of athletes and vehicles.

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