Question

A net force of magnitude 36 N gives an object of mass m1 an acceleration of 6.0 m/s^2. The same net force gives m1 and another object of mass m2 fastened together an acceleration of 2.0 m/s^2. What acceleration will m2 experience if the same net force acts on it alone?

Answer 1

This is a beautiful problem to test whether a student actually understands
Newton's 2nd law of motion . . . Force = (mass) x (acceleration).

That simple law is all you need to solve this problem, but you need to
use it a few times.

m₁ alone:
Force = (mass) x (acceleration)

36 N = ( m₁ ) x (6 m/s²)

m₁ = (36 N) / (6 m/s²)

m₁ = 6 kilograms .

m₁ and m₂ glued together:
Force = (mass) x (acceleration)

36 N = (6 kg + m₂) x (2 m/s²)

6 kg + m₂ = (36 N) / (2 m/s²) = 18 kilograms

m₂ = 12 kilograms .

m₂ alone:
Force = (mass) x (acceleration)

36 N = (12 kg) x (acceleration)

Acceleration = (36 N) / (12 kg)

Acceleration = 3 m/s²