Gravitational Acceleration Question

[jb2000tj]

Homework Statement

Calculate the maximum gravitational attraction between a man and an apple, when a) the apple was 1m from the man's center of mass, b) the apple hit his head. (man's mass 60kg, apple mass 100g)

Homework Equations

F=G(m_1)(m_2)/r^2
F=ma

The Attempt at a Solution

I set up the problem using the first equation F=((6.67x10^-11)*(60kg)*(0.1kg))/1 meter which came out to 4.002*10^-10. And for when the apple hit his head I got zero because F=((6.67x10^-11)*(60kg)*(0.1kg))/0. I guess my first question is would there be no gravitational attraction between the apple and the man when they are in contact? Does the gravitational attraction now become a weight force and normal force that cancel out?

 

[collinsmark]

Hello jb2000tj,

Welcome to Physics Forums! :)

Homework Statement

Calculate the maximum gravitational attraction between Sir Newton and the apple, when a) the apple was 1m from Sir Newton’s center of mass, b) the apple hit Sir Newton’s head. (Newton's mass 60kg, apple mass 100g)

Homework Equations

F=G(m_1)(m_2)/r^2
F=ma

The Attempt at a Solution

I set up the problem using the first equation F=((6.67x10^-11)*(60kg)*(0.1kg))/1 meter which came out to 4.002*10^-10.

That is correct, assuming a spherical Sir Newton.

And for when the apple hit his head I got zero because F=((6.67x10^-11)*(60kg)*(0.1kg))/0. I guess my first question is would there be no gravitational attraction between the apple and Newton when they are in contact? Does the gravitational attraction now become a weight force and normal force that cancel out?

It's not zero, but whatever the value is, there isn't enough information to solve the problem. Even if we assume a spherical Sir Newton they would be separated by Sir Newton's radius plus the apple's radius; we would need those radius values. Even if you modeled Sir Newton more realistically, we still need more information.