Velocity versus speed and philosophizing thereof

In summary, during a class discussion on the difference between velocity and speed, some students defined velocity as displacement divided by time and speed as distance divided by time. However, the concept of direction was not explicitly mentioned. The speaker suggests asking about the difference between displacement and distance to ensure understanding of the concept of direction. They also recommend discussing the concept of displacement before diving into velocity.
  • #1
Head_Unit
43
2
I asked a class of students what the difference was of velocity versus speed. The answer I was looking for was "direction" i.e. one is a vector. But a number of them said "Velocity is displacement divided by time, and speed is distance divided by time." Ignoring the second half of that assertion, I'm not sure what to say about the statement…because that is exactly what the equation says! (V=deltaX/t). To complicate things, "velocity" is ofttimes used colloquially and not in such a picky way. What would you say to the students who responded like this?
 
Physics news on Phys.org
  • #2
I would ask them what the difference is between displacement and distance. If the answer included that displacement involves direction (ie moved 10 metres to the East) whereas distance doesn't (ended up 10 metres from where it started), then I think the answer is good. They would still have captured the idea that velocity involves direction whereas speed does not.
 
  • #3
In this case, displacement is "how far you are from where you started" so I don't believe they are thinking about direction very explicitly. Probably they are just looking at the formula --> I can't say the answer is wrong, but it's not really right. I guess one thing I could do is to dissect that and say "note that displacement implies a DIRECTION"...
 
  • #4
I think that before discussing velocity you should make sure they understand the difference between displacement, distance and distance traveled.
 
  • #5
Perhaps ask them about situations where after some time the displacement is zero again.
 

FAQ: Velocity versus speed and philosophizing thereof

1. What is the difference between velocity and speed?

Velocity and speed are often used interchangeably, but they have different meanings in physics. Speed refers to the rate at which an object is moving, while velocity refers to the rate at which an object is moving in a specific direction. In other words, velocity takes into account both the speed and direction of an object's motion.

2. How are velocity and speed related mathematically?

Velocity is calculated by dividing the displacement of an object by the time it took to travel that distance. This means that velocity is equal to the change in position (displacement) divided by the change in time. Speed, on the other hand, is simply the distance traveled divided by the time it took to travel that distance.

3. Can an object have a greater velocity than speed?

Yes, an object can have a greater velocity than speed. This happens when an object is moving at a constant speed in a curved path, such as a car on a circular track. The speed may remain constant, but the velocity is constantly changing as the direction of motion changes.

4. How does acceleration affect velocity and speed?

Acceleration is the rate at which an object's velocity changes. When an object is accelerating, its velocity is changing, which means its speed is also changing. If the acceleration is in the same direction as the velocity, the object's speed will increase. If the acceleration is in the opposite direction of the velocity, the object's speed will decrease.

5. Can an object have zero velocity but non-zero speed?

Yes, an object can have zero velocity but non-zero speed. This happens when an object is moving in a straight line and its velocity is zero, but its speed is not zero. An example of this is a pendulum at the highest point of its swing. The pendulum has zero velocity at this point, but its speed is not zero because it is still in motion.

Similar threads

B Speed/velocity as a derivative
Replies
6
Views
1K
B Filming a passing road sign: speed vs bumpiness
Replies
16
Views
993
I Drag equation - relative flow velocity
Replies
11
Views
2K
What is the maximum velocity of a bullet at the instant it leaves the barrel?
Replies
5
Views
4K
Instantaneous Speed = Instantaneous Velocity?
Replies
7
Views
4K
Explaining usefullness of displacement and velocity
Replies
5
Views
2K
Two Equations for Average Velocity?
Replies
2
Views
2K
How to calculate velocity based on distance and time?
Replies
7
Views
3K
Angular Velocity or Angular Speed?
Replies
4
Views
4K
The use of the terms speed & velocity
Replies
7
Views
3K

Hot Threads

Recent Insights

Back
Top