Question

What does it mean when a change in velocity is negative?

Answer 1

when the change in velocity is negative it means there is some obstruction in the path of the object or wave

Answer 2

$\huge \bold{heya}$

$\bold \blue{velocity}$
Rate of change of displacement know as velocity.

yes definately it would be negative.
when it would moves in negavite direction the rate of velocity would be negative.

and it know as
$\bold{negative \: velocity}$
'The rate of change of velocity is know as acceleration ...
and if any body moves in -ve direction it's know as retardation.

$hope \:it \: will \: helps \: u$