Question

If an object/disc/anything, in motion and has accelerated does that mean there is more energy/kinetic energy? Generally when an object accelerates what does it mean? More what exactly?

Answer 1

@aaronq @Loujoelou @ganeshie8

Answer 2

@Australopithecus @tkhunny

Answer 3

@hartnn

Answer 4

@eSpeX @nincompoop

Answer 5

Could you clarify your question a bit? An object in motion has to have accelerated at some point. Typically "acceleration" comes down to a change in direction or state. If an object turns, it is accelerated, if an object goes from rest-motion or motion-rest, it also is accelerated.

Answer 6

Generally if an object is accelerated does that mean there is a change in kinetic energy or increase in energy? @eSpeX
Generally does acceleration indicate an increase or change in energy?

Answer 7

I would say that yes it does although not always an "increase". If an object is undergoing acceleration to slow it down, your velocity gets smaller and thus your kinetic energy, 1/2mv^2, gets smaller. A similar effect occurs if your acceleration increases the velocity of the object.

Answer 8

In what case can an object go through an acceleration to slow it down :S ? I thought acceleration would always increase an objects velocity.

Answer 9

Well you know that F=ma, so the force of friction, which slows something down, adds a little acceleration in the direction opposite of travel. A car braking or decelerating is going through a negative acceleration.

Answer 10

When you throw an object into the air, you accelerate it upward, at the same time the earth (gravity) accelerates in the opposite direction (negative acceleration with respect to your throw).

Answer 11

OOw ok! So the proper answer to my question would be: It depends.
If I were to increase a car's acceleration I would increase its total energy but at the same time I'm increasing friction that is causing a negative acceleration which is basically decelerating the car.

Im I on the right page here?

Answer 12

You have the right idea, but the +/- acceleration has more to do with how you define your coordinate system than the 'type' of force you are applying.

Answer 13

The force of a mass on a spring for example, the spring always pulls towards equilibrium. You might say that that was a "positive" force, however, that force is always applied against the motion so if the spring force was positive then the mass would be going through a negative motion based on those coordinate.

Answer 14

Thanks @eSpeX generally I got the idea now thanks. So if I noticed an object accelerating it would mean that generally! There is an increase of energy when an object is accelerated "generally speaking".

Answer 15

Yes, generally speaking you should say that it is a "change" of energy when an object is accelerated.

Answer 16

In a linear motion, acceleration implies change in kinetic energy.

But in other types of motion, you can have acceleration (change in velocity) without change in speed. In that case, there is no change in kinetic energy.

To achieve that, the force producing the acceleration has to act at right angles with the velocity.

Answer 17

@Vincent-Lyon.Fr In case of rotational motion an acceleration of a disc,wheel,gear that means there is a change in Rational Kinetic energy. Because that is an increase of RPM and possibly torque?

Answer 18

Not sure about the torque because I remembered the "RPM/TORQUE" graph so I'll keep this asaide for a bit.

Answer 19

I wouldn't say positive or negative acceleration.. i would use the word acceleration and deceleration ..

anyways when you accelerate an object you have to put a force on it.. and hence +ve work is done and thus that work is manifested as the increase in the kinetic energy of the body.. So its more like.. you are transferring your energy into the body so to speak

similarly when you decelerate an object.. you do negative work.. so its KE decreases... its more like you are TAKING energy from the object..

however.. when a CENTRAL force acts on an object.. ( force of gravity, electrostatic force etc).. then the force and displacement (instantaneous) are perpendicular.. in other words the force only CHANGES its direction.. (when you swing a ball tied to a thread maybe).. in that case.. no work is done.. and hence.. there is no change in the kinetic energy EVEN though it is being accelerated.. (centripetal acceleration).. centripetal acceleration is THE only kind of acceleration which does not change the SPEED of the body (velocity changes only cause the direction is continuously changing).. and the body describes what is called as a uniform circular motion!

Answer 20

Yet a disc's/wheel/gear's acceleration is an increase o Kinetic energy right? Surly it is...
@eSpeX
@Mashy
@Vincent-Lyon.Fr

Answer 21

What is the specific question you are trying to answer? Making broad generalizations will only lead to confusion. The safest thing I can think of to say that relates acceleration to kinetic energy is this, when you accelerate an object you change the "state" of that object. If you are speeding it up you are typically putting "energy" into the system, if you are slowing it down you are typically "removing" energy from that system.
The problem is, you can really lead yourself astray depending on how you define the system in each case if you try to apply a broad generalization. You might be accelerating one piece of a system that has a negative effect on the system as a whole, such that the total kinetic energy may be transferred into something to cause an apparent decrease. Much like my comments with the coordinate system it will greatly depend on your perspective and how you are defining what you are working with.

Answer 22

@eSpeX Thanks!
Thank you everyone for your help and inputs. I pretty much understood the answer to my questions generally is a yes.