A question on motion (1 Viewer)

[jyu]

An object has an acceleration to the right. Which one or more of the following statements is/are correct?

A. The object could be moving to the right.
B. The object could be moving to the left.
C. The object could be moving upwards.
D. The object could be moving downwards.
E. The object could be moving at an angle to the horizontal.
F. The object could have zero speed.

:wave:

 

[Bank$]

I would say all of the obove except "F" that is considering that the object was already moving in some sort of way.

 

[kony]

all are possible.

 

[forevaunited]

Ok saying that the object has acceleration means that it must be moving? So for me i would chuck out f.) Actually i was just about to say that i personally thought that moving to the left was impossible as well but the other two posters have got me doubting myself.

Like are you saying that an object could be moving to the left but some force or something is giving it acceleration towards the right ie. that its speed to the left is being slowed or decreased because of the acceleration to the right?

having said that, i suppose an object could have acceleration to the right that is being completely counter balanced by acceleration to the left. ie. it has zero speed meaning that f) could be possible. hmmm well ive done a very good job of thoroughly confusing myself

 

[kony]

hmm, well this is my reasoning:

1. suppose it before the acceleration was applied, the object was stationary. now apply a force to the right. it will accelerate to the right, and thus move to the right.

2. suppose a meteor is moving left, suddenly a large mass appears on its right. the gravity will cause it to accelerate to the right, and thus reduce its speed, but overall, it may very well be moving still to the left.

3. suppose there is a wall on the objects right. the object is travelling up the wall. then a huge mass is put into place on the other side of the wall, causing the acceleration to the right. the object still travels up, because of the physical barrier.

4. same as above.

5. suppose an object is moving up. then a large mass is put into place on its right. it would start moving in a north-eastern direction at that instant.

6. suppose an object is at rest against a wall running up and down. now a large mass is put on the other side of the wall. the object cannot move, and has 0 speed.

if the wall thing is allowed, i think this is valid.

 

[Forbidden.]

Is displacement taken into account or are the measurements using scalars ?

 

[xiao1985]

all are possible.

velocity and acceleration does not have any bearing on each other (although velocity will ultimately be affected by accelerationg, true)

 

[jaaaaay]

All are possible. *nods* =]

 

[Bank$]

Can someone pls explain how "F)" is possible

 

[bos1234]

how is bcdef possible?

 

[xiao1985]

even if the object is initially stationary, applying a force to the right would cause an acceleration to the right. except at the very first instant, it has zero speed (stationary), but acceleration to the right (due to the force being applied)

 

[twilight1412]

all possible but F
as it must have speed of somesort .... unless of course there is an unmentioned acceleration to balance out the acceleration to the right which would result in zero acceleration = zero speed

backing up forevaunited XD (didnt see his post till i finished typing ..)

UNLESS!!!!!!

B is possible because if the initial motion to the left is relatively large compared to the acceleration to the right it will still experience a motion towards the left until such point where there will be zero speed INSTANTANEOUSLY and move to the right

 

[xiao1985]

at the instant which force is applied, the object can have zero speed...

even if the object has an initial velocity to the left, some point along the way, it will have a velocity of zero (hence speed of zero)

 

[Bank$]

but is there any way for the object have zero speed and maintain it ????

 

[xiao1985]

but is there any way for the object have zero speed and maintain it ????

no, but the question doesn't ask if you need to maintain it

 

[jyu]

An object has an acceleration to the right. Which one or more of the following statements is/are correct?

A. The object could be moving to the right.
B. The object could be moving to the left.
C. The object could be moving upwards.
D. The object could be moving downwards.
E. The object could be moving at an angle to the horizontal.
F. The object could have zero speed.

:wave:

You find out the instantaneous motion of an object from its velocity, not from its acceleration. Since the velocity is not given, all the answers A to F are correct.

Acceleration is related to the net force on the object according to Newton. If the acceleration is to the right, the net force is to the right. That is all you can say.

Regarding answer F, consider an object projected vertically upwards. At its highest point it comes to a stop momentarily but its acceleration remains the same value g vertically downwards because the force of gravity is still there.