Why does only constant speed accelerate and not constant velocity?

[gagneana000]

I know barely anything about Physics and this is the 1st Physics Class I've been in.

Homework Statement

Why can only a constant speed accelerate and not a constant velocity?

Homework Equations

None

The Attempt at a Solution

No idea...

Please help!

 

[Niriz]

Since speed it a scalar quantity it only refers to how fast an object is moving. Velocity is a vector, meaning that its speed AND direction are important. Acceleration is also a vector quantity, so if an object's movement either changes direction, or goes faster, there is aceleration.

If an object is moving at constant speed, it could change directions which is a form of acceleration, but it would still be going at the same speed.

However, if an object is to be moving with constant velocity, it's speed and direction cannot change for it to be constant. It cannot accelerate

 

[gagneana000]

Since speed it a scalar quantity it only refers to how fast an object is moving. Velocity is a vector, meaning that its speed AND direction are important. Acceleration is also a vector quantity, so if an object's movement either changes direction, or goes faster, there is aceleration.

If an object is moving at constant speed, it could change directions which is a form of acceleration, but it would still be going at the same speed.

However, if an object is to be moving with constant velocity, it's speed and direction cannot change for it to be constant. It cannot accelerate

Oh, that makes sense! Thanks! So Vector means that speed and direction are important? What is a "scalar quantity?" Thanks though :)

 

[Niriz]

scalar means only the magnitude, or size is important.

So in the case of speed and velocity, the 'magnitudes' of their motion is how fast they are going

 

[gagneana000]

I'm still not understanding... sorry, but what do you mean their size and magnitudes? What does size have to do with speed?

 

[gagneana000]

I looked up the word scalar, so it's almost the opposite of Vector, it's when a quantity only relies on speed and not direction?

 

[fizzynoob]

a scalar does not have a direction, it is just some quantity, for example temperature is a scalar since it does not have a direction. Speed is also a scalar

 

[gagneana000]

a scalar does not have a direction, it is just some quantity, for example temperature is a scalar since it does not have a direction. Speed is also a scalar

Okay, I think I understand! Thanks a lot! Hopefully I'll get better in Physics!