How high was the package above the ground when it was thrown

[Perseverence]

Homework Statement

( p 49 sterling)
Ignoring air resistance, if it takes 16 seconds for a package to strike the ground, how high above the ground was a package when it was thrown upward from the stationary helicopter at 15 m/s per second[/B]

Homework Equations

V=Vo+at
D=Vot+(1/2)at^2

The Attempt at a Solution

It seems pretty straightforward that the solution would be the distance from the initial throw upward to the upward velocity becoming zero.
V=Vo+at
0=15+(-10)t
1.5 sec =time (to Vy=0)

Then plugging in 1.5sec into
D=Vot+(1/2)at^2 to get 11.28m. But that is not the solution in the book. The solution in the book is 1040m.

 

[lekh2003]

Homework Statement

( p 49 sterling)
Ignoring air resistance, if it takes 16 seconds for a package to strike the ground, how high above the ground was a package when it was thrown upward from the stationary helicopter at 15 m/s per second[/B]

Homework Equations

V=Vo+at
D=Vot+(1/2)at^2

The Attempt at a Solution

It seems pretty straightforward that the solution would be the distance from the initial throw upward to the upward velocity becoming zero.
V=Vo+at
0=15+(-10)t
1.5 sec =time (to Vy=0)

Then plugging in 1.5sec into
D=Vot+(1/2)at^2 to get 11.28m. But that is not the solution in the book. The solution in the book is 1040m.

You are making a massive mistake and missing steps. You are calculating how far up the book will go when its velocity becomes 0. That is 11.28.

However, the question asks for how high up the helicopter is, not how high the book went up before it became 0.

Try again.

 

[Perseverence]

You are making a massive mistake and missing steps. You are calculating how far up the book will go when its velocity becomes 0. That is 11.28.

However, the question asks for how high up the helicopter is, not how high the book went up before it became 0.

Try again.

if you are in a helicopter and something in the air, when it reaches as high as it will go, it's Vertical Velocity will be zero. That is the distance from the helicopter

You are making a massive mistake and missing steps. You are calculating how far up the book will go when its velocity becomes 0. That is 11.28.

However, the question asks for how high up the helicopter is, not how high the book went up before it became 0.

Try again.

Oh my gosh
You're right, I was calculating the wrong distance! I figured out what I was doing wrong. Thank you so much for your help!

 

[lekh2003]

Oh my gosh
You're right, I was calculating the wrong distance! I figured out what I was doing wrong. Thank you so much for your help!

It's good that you realized. You're welcome.

 

[Dr Dr news]

The equation you are looking for is the kinematic equation for 1D vertical motion with no air drag. y = y0 + v0 t - gt^2 / 2 , t is the time of flight from y0 to y=0.