Calculating Force

[jwest22]

Hello, im struggling with what should be a simple problem but I just cant get my head around it.

 

Basicly, if 8kg is needed to move an object horizontally at 0.25m/s what is the force?.

(It's not just f=ma is it?).

 

Thank you

[Kyrisch]

That doesn't make much sense... If it's moving at a constant speed (0.25 m/sec) there would be no net force acting on it at all. If you meant 0.25 m/sec^2, the question still doesn't make sense phrased as it was. 2 Newtons of force, however, is required to accelerate an 8 kg object at 0.25 m/sec^2 (F = ma).

[Klaynos]

Or it does make sense and it's a trick question.

 

F=ma

 

a = 0

 

F=m0

 

F=0

[mrburns2012]

No force, unless there's friction and/or there's an incline.

[cameron marical]

klaynos, how did you come up with those answers?

[Klaynos]

What is the acceleration on the body?

[swansont]

Basicly, if 8kg is needed to move an object horizontally at 0.25m/s what is the force?.

 

8 kg is a mass. Saying that a certain mass is needed to move an object makes no sense. Something is missing or mis-stated.

[jwest22]

Sorry, I wrote that in a really stupid way. Let me try and rephraise it. If an object is sitting on a surface, and a piece of string is attached to the object with an 8kg weight on other end, the weight is then dropped off the edge of the surface, and the object is pulled along at 0.025m/s (friction can be ignored). Therefore how much force is needed to move that object?

 

Does that makes any sense, or have I just made a total hash of it?

[swansont]

Sorry, I wrote that in a really stupid way. Let me try and rephraise it. If an object is sitting on a surface, and a piece of string is attached to the object with an 8kg weight on other end, the weight is then dropped off the edge of the surface, and the object is pulled along at 0.025m/s (friction can be ignored). Therefore how much force is needed to move that object?

 

Does that makes any sense, or have I just made a total hash of it?

 

If it moves at a constant speed, then there must be zero net force. The force you describe is 8 kg * 9.8 m/s^2, and that's how much force you need to apply in the opposite direction to keep the speed constant.

[jwest22]

I've been getting confused between velocity and acceleration. If the intial velocity is 0 and the final velocity is 0.025m/s over 10s, the the accelleration:

a=0.0025m/s^2

So, where does that leave me with the force, presumable not just f=ma as that would equate to 0.02newtons?

[Klaynos]

The force over the 10s assuming it's constant it's just f=ma, why would it not be?

[swansont]

I've been getting confused between velocity and acceleration. If the intial velocity is 0 and the final velocity is 0.025m/s over 10s, the the accelleration:

a=0.0025m/s^2

So, where does that leave me with the force, presumable not just f=ma as that would equate to 0.02newtons?

 

If that's the motion of the 8 kg object, then yes. You're describing a small mass, speed and acceleration, so getting a small force shouldn't be surprising.