Why is it that you might feel the effect of gravitational forces between you and Earth, but not between you and a classmate?

Because the mass of the the earth is way bigger than the mass of a classmate

Explanation:

Formula for force of gravity is;

F = Gm1•m2/r²

Where m1 and m2 are the two objects masses in question.

So, m1 may be your mass while m2 may be either the mass of the earth or your classmate.

The bigger the mass of m2, the more the force of gravity

Mass of the earth is about 5.97 × 10^(24) kg is which is so much more bigger than that of the classmate which is a human being.

Therefore, the reason why you may feel the effect of the gravitational forces between you and Earth, but not between you and a classmate is probably because the mass of the the earth is way bigger than the mass of a classmate