Students tend to confuse velocity with acceleration. This confusion has been documented by many physics educators (just a simple search of “student understanding of velocity, acceleration” on Google Scholar will do). This mixing of ideas follows students from high school to undergraduate.
One may think that as technological advances, the teachers are well-equipped with modern learning tools, students would be able to learn and retain information better.
Many factors contribute to the learning and retention of new information. I would see this misconception as part of the learning journey of getting better at physics.
Back to the topic of velocity and acceleration, how can teachers do to help students to distinguish them better?
For teachers
At the University of Washington, the Physics Education Research Group has designed a worksheet to help students understand the relationship between velocity and acceleration. Details can be found here.
In that worksheet, it emphasizes several physical quantities: velocity, change in velocity, and acceleration.
Why so? Their research found that part of students’ confusion came from not distinguishing velocity and change in velocity. Questions are designed so that students can differentiate between the above-mentioned quantities.
There is also a strong emphasis on applying the definition of change in velocity and acceleration correctly.
Here are the walkaway messages from the exercise.
- Object speeds up: Its velocity and acceleration are in the same direction.
- Object slows down: Its velocity and acceleration are in the opposite direction.
- Object at uniform motion: Its acceleration is zero.
For students
What should students do when it comes to solving problems related to velocity and acceleration?
Look for phrases such as “speeding up,” “slowing down,” “constant speed,” “uniform motion” and other equivalent terms in the question. This information tells you the sign of the acceleration of the object relative to its velocity. Speeding up would mean both velocity and acceleration are of the same signs (could be both positive or both negative); slowing down would mean they are of opposite signs, and uniform motion means acceleration is zero.
Depending on your level (secondary school, pre-university, college), you will see this in 1D motion and projectile motion most of the time.
Wrapping up
It is important for you to distinguish between velocity and acceleration because it will affect your understanding between force and velocity.
Chang Physics Class 