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# Can an object be accelerating and yet -not- moving?

MattDavis

1
Wed 27 Feb, 2013 07:30 pm
@dalehileman,
You would eventually understand it. It's just a matter of time invested.
Follow wherever your interests take you. If that question is important to you, I will try to point you in the right direction.
dalehileman

0
Wed 27 Feb, 2013 07:33 pm
@MattDavis,
Quote:
I will try to point you in the right direction.
I feel honored
0 Replies

north

1
Fri 8 Mar, 2013 07:08 pm

I just thought of this scenario

A car for example , parked

But the Earth is accelerating , rotation

Hence the car is not moving , but is accelerating

dalehileman

1
Sat 9 Mar, 2013 11:46 am
@north,
Quote:
Hence the car is not moving , but is accelerating
That's a good q, North, a matter about which I've long wondered. Whereas the gravity is pulling straight down, isn't any force on account of rotation pulling at a slight angle
0 Replies

contrex

1
Sat 9 Mar, 2013 12:39 pm
Hey! this could be exploited to make flying cars like on the Jetsons!
dalehileman

2
Sat 9 Mar, 2013 12:42 pm
@contrex,
Hasn't someone already broached the possibility, that is, for some reason gravity quits or the Earth stops rotating

Seems however we're just a bit OT here. "Can an object be accelerating and yet-not-moving?", almost everyone in the affirmative

…..except me, I have this nagging feeling that the ball actually stops up there, and on a purely mathematical basis, namely that its reversal at the top is, though infinitesimal, a stop; a point at which the graph is horizontal

Again I'm no mathematician (as I'm sure you will agree) but I have this intuitional take: Just as there are different kinds of infinities (for instance based on different rates of development), there are also different kinds of zeroes
0 Replies

Brandon9000

2
Thu 15 Feb, 2018 04:45 am
@rosborne979,
rosborne979 wrote:
Are you sure the definition of acceleration accurately describes the object right at the moment in time when it's velocity becomes zero.

Acceleration is the rate at which the velocity of a body changes with time. So if you're talking about a tiny moment of time when velocity is essentially zero, then both time and velocity equal zero in that definition, and there can be no "rate of change" as the moment of time approaches zero.

Sorry, but no. When you throw a ball up in the air and it slows until it stops, at that instant, its velocity is 0, but it's acceleration is 32 ft/sec^2 downwards. An object's may have any velocity paired with any acceleration.
maxdancona

1
Thu 15 Feb, 2018 06:09 am
@Brandon9000,
I have Physics degree and taught Physics.

Brandon is 100% correct.
0 Replies

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