Students use compensation arguments to incorrectly solve conceptual problems.

Two blocks, one with twice the mass of the other, start from rest. They experience the same constant force for 1 s. Compare their kinetic energies after the force has been applied.

  Correct Answer

Two blocks, one with twice the mass of the other, start from rest. They experience the same constant force for 1 m. Compare their momenta after the force has been applied.

  Correct Answer

Students who have this difficulty will make claims that they larger mass will balance out the effect of the smaller velocity, to cause the final momenta and kinetic energies to be equal in questions like these. 

Related misconceptions/student difficulties that may arise in the question:

 Students who do well in quantitative problem solving have difficulties with purely conceptal problems.