Can an object be accelerating when its speed is zero?

[rfmason_2000]

[S_C]

zero speed equals no movement , therefore no acceleration

[joggerjayne]

Is this a trick question ?

[S_C]

a trick question , its a bit vaigue for that as you can in a car for instance accelerate both backwards and forwards , and as no direction is stated , if it is a trick question its not exactly very clear

[vascop]

Yes, of course an object which has zero velocity can be accelerating. If you throw a ball up into the air, it eventually stops instantaneously and then starts coming back down. At that same point (where it stops), it has an acceleration in the downward direction due to gravity. If it didn't, it would stay where it was suspended in mid air.
Acceleration is what causes a change in velocity.

[bibblebub]

if you don't know the difference between speed and acceleration then don't get your hopes up too high for that school physics exam

[rov1200]

Not according to Newton's Laws

[bibblebub]

^^^ that's not what Newton's laws say, otherwise a pendulum bob when it reaches the height of it's swing would just stop there, suspended in the air.

[Old_Geezer]

Beware of confusing the issue by considering just an instant in time: to accelerate one needs change over time.

[vascop]

OldGeezer
No, it's perfectly possible to have an instantaneous acceleration and an instantaneous velocity.

[vascop]

That's what the differential calculus is all about.

[bibblebub]

oh no don't mention calculus, these people are struggling with just the basics

[vascop]

Calculus IS the basics!

[bibblebub]

I know that, you know that, but those who seem to think that a fly can stop a train might struggle.

[ABerrant]

vascop - why did you rephrase the question in terms of velocity instead of speed?

[bibblebub]

Velocity is a vector quantity, i.e. has direction and its magnitude is speed, and general equations of motion are in terms of vectors not scalar quantities.

[ABerrant]

Precisely - since the question is scalar why introduce vectors? A body with zero velocity can still have quantifiable speed in scalar vernacular.

There may be many accelerating forces acting upon the body but if the net effect is no speed then, in scalar vernacular, that body is not accelerating for the entire time the speed remains zero.

[vascop]

Aberrant (;-)
Forces produce acceleration.
A body with zero velocity also has zero speed.

[ABerrant]

I am not disputing the Physics or Calculus of the rephrased question, just that you did not answer the question as asked (as vague as that is and has been pointed out).

[Old_Geezer]

Even instantaneous acceleration needs a trend over time. Motion at an instant is just mathematician's faith in their calculations.

[mollykins]

if its velocity is zero than it can be, as it could be accelerating from a velocity of -5 to +5 which means, that at some point its velocity or 0 but its still accelerating. I don't know if this is what you meant as you specify speed not velocity.