Solving Force Problems: Divide Weight of Plane by Gravity?

[Dberry]

1. The problem
An airplane's propellers exert a force on the plane of 2500N to the east. Wind resistance of 500N acts to the west. If the weight of the plane is 40,000N, what is the acceleration of the plane?

Homework Equations

F=ma

The Attempt at a Solution

I have the solution from the back of my book but I don't understand the method fully.

I know the net force on the plane is 2500N-500N=2000N east.
Then it says divide 40,000N by 10 (gravity) =4,000N
And then plug the numbers into F=ma.

The part I don't understand is why do you have to divide the weight of the plane by gravity?

Thanks for your help!

 

[Doc Al]

The part I don't understand is why do you have to divide the weight of the plane by gravity?

You need the mass of the plane, but you're given its weight. How are they related?

 

[p21bass]

1. The problem

The part I don't understand is why do you have to divide the weight of the plane by gravity?

Do you know what the, for lack of a better term, "definition" of the weight is? Or at least how it relates to the mass?

 

[Dberry]

Weight is mass times gravity right? Ok that makes sense now. Thank you!

 

[p21bass]

Weight is mass times gravity right? Ok that makes sense now. Thank you!

Weight is the mass * the acceleration due to gravity. So, basically yes - but make sure you understand that the 10 (or in some texts, 9.8 or 9.81) is actually 10 m/s².

Just a tip - always check/write your units, so that you can verify that your answers come out as expected.

 

[Dberry]

Weight is the mass * the acceleration due to gravity. So, basically yes - but make sure you understand that the 10 (or in some texts, 9.8 or 9.81) is actually 10 m/s².

Just a tip - always check/write your units, so that you can verify that your answers come out as expected.

Yes I understand. Will do!