# Normal force on the landing gear when the airplane lands

1. Oct 13, 2014

### Wapapow10

1. The problem statement, all variables and given/known data
An airplane of mass 25,000 kg (approximately the size of a Boeing 737) is coming in for a landing at a speed of 72 m/s. Calculate the normal force on the landing gear when the airplane lands. Hint: You will use 0.92 m as the compression (vertical displacement) of the landing gear shock absorbers when the plane contacts the ground and 5° as the angle that the landing velocity makes with the horizontal.

2. Relevant equations

3. The attempt at a solution
plane N 9.8*25000=245000N
a=vf^2-vi^2/2*-.92=36.31m/s
Fn=245000=25000*36.31=664750N*******
dy=-.92
viy=-6.27
vfy=0
a=36.39

Not sure what im doing wrong

Last edited: Oct 13, 2014
2. Oct 13, 2014

### rude man

When the landing gear first touches the ground, what is the normal velocity? What is the normal kinetic energy? Can you somehow equate that energy with the work the force does as it travels over the 0.92m?

3. Oct 13, 2014

### Wapapow10

I thought thats why I did 0-6.7^2/2*9.2
44.89/1.8=24.93

sorry I had to I was mixing numbers from another question.

4. Oct 14, 2014

### rude man

I can't figure out your numbers since you didn't define where they came from.

I should have added that in addition to the change in kinetic energy of the plane at the beginning and at the end of the 0.92m descent, there is also a loss of potential energy. Both are reduced by the action of the force over the given vertical distance.

Last edited: Oct 14, 2014