Equations of uniformly accelerated motion
2 marks · EasyA physics student says: “If an object travels with constant acceleration, you can always use the equation to solve for any one of the variables.” Explain one limitation of this equation in solving real-life motion problems.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
The equation only works if the acceleration is constant (uniform), which is not always true in real life (e.g. when there is changing force or air resistance).
Must show: Mentions uniform/constant acceleration requirement
Also accept: It only applies when acceleration is constant.; It is not valid if acceleration changes (e.g. due to air resistance).
Common mistakes: Saying it applies to all situations; Not specifying constant acceleration
Show mark scheme and worked solution
Marking points
B1 · 1 mark · States or implies the formula is only valid for constant/uniform acceleration
B2 · 1 mark · Gives a correct reason/example why real-life motion may not by constant acceleration (e.g. changing forces/air resistance)
Worked solution
The equation only works for objects accelerating at a constant rate. In real life, acceleration may change, for example if air resistance acts. Then this formula does not apply.