Kinetic projectile motion (Helicopter questions)

In summary, the conversation was about finding the time it takes for a coke bottle to hit the ground when dropped from a helicopter. Various formulas were discussed, but the final solution involved using the formula y = y_o + v_o*t + a*t^2/2. The conversation also mentioned that factoring and using quadratic equations were not allowed in this particular problem.
  • #1
bbalin23
5
0

Homework Statement



A helicopter flies upward at 3.0m/s. The pilot drops a coke bottle when the helicopter is 30.0m above ground. How long will it take the coke bottle to hit the ground?
(2.8s)

*Note* We can't factor or use quadratics to solve

Homework Equations


The Attempt at a Solution



First I tried to calculate the distance the coke bottle will go upward before falling downward:

Vf2-Vi2/2a = d

9/19.62

0.459

Then I added that to the distance... D(total) = 0.459m + 30.0m = 30.459m

Then I attempted to find the time from there using the formula:

d = vi(t) + 1/2 a t(squared)

Vi from the maximum height (Total distance) is zero so

Sqrt(2d/a) = t

Sqrt(60.918/9.81)
Sqrt(6.20978)
t = 2.4919
= 2.5s

Im off by .3 please help!
 
Last edited:
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  • #2
Just use the equation normally. Don't calculate the first thing you did.

So basically just use:
[itex]d=v_{i}t-4.9t^{2}+h[/itex]
h being the initial height.
Then you'll end up factoring and have 1 of the answers
 
  • #3
iRaid said:
Just use the equation normally. Don't calculate the first thing you did.

So basically just use:
[itex]d=v_{i}t-4.9t^{2}+h[/itex]
h being the initial height.
Then you'll end up factoring and have 1 of the answers

Sorry I forgot to mention it earlier but we weren't supposed to factor or use quadratic equations :(
 
  • #4
You only need one formula,

y = y_o + v_o*t + a*t^2/2

You know y_o, v_o, and a
 
  • #5
Spinnor said:
You only need one formula,

y = y_o + v_o*t + a*t^2/2

You know y_o, v_o, and a

I'm not sure which formula that is unfortunately as its not on my formula sheet, so I don't think I would be allowed to use it.
 
  • #6
Why can't you factor lol?
 
  • #7
iRaid said:
Why can't you factor lol?

Apparantly we are supposed to be able to figure this out without factoring (She says its to refrain us from using calculus later on in the course as if we do we won't get marks on the question)
 
  • #8
Thanks everyone I figured it out using a couple different formulas! Thanks for helping!
 

1. What is kinetic projectile motion?

Kinetic projectile motion refers to the movement of an object through the air due to the force of gravity. It involves the object being launched or dropped at a certain angle and speed, and then following a curved path known as a trajectory.

2. How does helicopter movement relate to kinetic projectile motion?

Helicopters use the principles of kinetic projectile motion to stay in the air. The blades of a helicopter act as rotating wings, generating lift and causing the helicopter to move upwards. The angle and speed of the blades determine the helicopter's trajectory and movement.

3. What factors affect the trajectory of a helicopter?

The trajectory of a helicopter is affected by several factors, including the angle and speed of the blades, the weight and balance of the helicopter, and external factors such as wind and air pressure. The shape and design of the helicopter also play a role in its trajectory.

4. How does air resistance impact a helicopter's kinetic projectile motion?

Air resistance, also known as drag, can have a significant impact on the trajectory of a helicopter. As the helicopter moves through the air, it experiences resistance from the air molecules, which can slow it down and alter its trajectory. Helicopter designs often take air resistance into account to improve efficiency and control.

5. How is kinetic projectile motion used in helicopter navigation?

The principles of kinetic projectile motion are crucial in helicopter navigation. Pilots must understand how the helicopter moves through the air and how external factors can affect its trajectory. They also use this knowledge to make adjustments to the helicopter's angle and speed to control its movement and reach their destination safely.

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