# Velocity and acceleration of an airplane

## Homework Statement

VELOCITY AND ACCELERATION:
An airplane lands in a carrier deck at 150 miles per hour and is brought to a stop by an arresting device in 500 feet.

## Homework Equations

What is the acceleration?
What is the time required to stop?

## The Attempt at a Solution

Hootenanny
Staff Emeritus
Gold Member
Welcome to Physics Forums.

You seemed to have missed a section:

## The Attempt at a Solution

welcome to physics forums.

You seemed to have missed a section:

what do you mean????

Hootenanny
Staff Emeritus
Gold Member
what do you mean????
You haven't showed us your attempt at the solution.

You haven't showed us your attempt at the solution.

BUT i've got no idea how...., i don't know because the given variables are only two which are: the distance, velocity but in physics formula for the computation of this problem requires three or more than variables given.. could you teach me???

Hootenanny
Staff Emeritus
Gold Member
BUT i've got no idea how...., i don't know because the given variables are only two which are: the distance, velocity but in physics formula for the computation of this problem requires three or more than variables given.. could you teach me???
You actually know three variables:
1. Distance
2. Initial Velocity
3. Final Velocity

You actually know three variables:
1. Distance
2. Initial Velocity
3. Final Velocity

could you tell me what is the initial and final velocity... if i will be able to know that, then i think i could do it..... thank you so much....

Hootenanny
Staff Emeritus
Gold Member
could you tell me what is the initial and final velocity... if i will be able to know that, then i think i could do it..... thank you so much....
I'm sure that you could work that out for yourself. You are given the initial speed and you are told that the aircraft comes to rest. What is the aircraft's speed when it isn't moving?

I'm sure that you could work that out for yourself. You are given the initial speed and you are told that the aircraft comes to rest. What is the aircraft's speed when it isn't moving?

zero???

Hootenanny
Staff Emeritus
Gold Member
zero???
Exactly

Exactly

oh... so half of 150 gives if velocity = (Final velocity + Initial velocity) / 2, then, it will give me a 75 average velocity right?

Hootenanny
Staff Emeritus
Gold Member
oh... so half of 150 gives if velocity = (Final velocity + Initial velocity) / 2, then, it will give me a 75 average velocity right?
Why are you computing the average velocity?

oh... so half of 150 gives if velocity = (Final velocity + Initial velocity) / 2, then, it will give me a 75 average velocity right?

THANx Hootenanny... :) i know this is just a simple problem yet i don't know how to solve it.... thanx a lot.... more powers!!!

Hootenanny
Staff Emeritus
Gold Member
THANx Hootenanny... :) i know this is just a simple problem yet i don't know how to solve it.... thanx a lot.... more powers!!!
You should be able to use kinematic (SUVAT) equations to solve this.

Why are you computing the average velocity?

To find the time needed to come to a stop with: avg velocity = distance/time

To find the time needed to come to a stop with: avg velocity = distance/time

yet there's no time indicated from the given problem making me think about the velocity to get the time.... can you help me with this?? thanx a lot...

v0 = 150 mph = 67.1 m/s
v1 = 0 m/s
$$\Delta$$x = 500 ft = 152.4m

use v12 = v02 + 2a$$\Delta$$x

I think you can solve it from there?

yet there's no time indicated from the given problem making me think about the velocity to get the time.... can you help me with this?? thanx a lot...

You are on the right track. Use the average velocity to get the time required to stop.

There is also a kinematic formula that can give you the answer directly.

You are on the right track. Use the average velocity to get the time required to stop.

There is also a kinematic formula that can give you the answer directly.

i'll try.... thank u so much.. :)