Freefall v Jetpack: Will He/She Stay Afloat or Crash?

[Dhruvish]

Homework Statement

There is a random person falling from the sky. He remembers that he has a jetpack. Unfortunately, his jetpack is weak and is only able to provide upward force equivalent to Fg.

WILL HE?SHE STAY AFLOAT OR WILL HE?SHE CRASH INTO THE GROUND?
What acceleration will he/she hit the ground?

Homework Equations

um, none

The Attempt at a Solution

I mean logically speaking, the person should stay afloat since the force of gravity is equal to the jetpacks force.

 

[kuruman]

Is Fg a force equal to the person's weight?

 

[Dhruvish]

picture below illustrating the question.

 

[donpacino]

F=ma

so for some time period a person is accelerating. He now a speed S
Assuming Fg is the force required to cancel out the effect of gravity, that means his acceleration will equal zero. what is his speed?

 

[Dhruvish]

the question does not specify speed, just mentions the force of gravity and the upwards countering force.

 

[donpacino]

the question does not specify speed, just mentions the force of gravity and the upwards countering force.

Yes it does mention speed, it just doesn't matter exactly what that speed is.

There is a random person falling from the sky.

in order for a person to be falling, they must have speed. If acceleration =0, what happens to speed

 

[Dhruvish]

so, what is the final conclusion, Does the person fall or stay afloat? and if fall at what acceleration?

 

[donpacino]

so, what is the final conclusion, Does the person fall or stay afloat? and if fall at what acceleration?

I'm not going answer it for you...

lets try this.

jetpack man is at 1000 feet (a distance)
he falls 100 ft/s (a speed)

his speed doesn't change

what happens his altitude over time. remember that distance = speed * time