Force and acceleration in object at rest

In summary, the acceleration of an object that is at rest and being pulled by a rope with increasing force is constant and 0. This is because the object is not moving, so its velocity (and therefore acceleration) is 0. However, the net force on the object is the force being applied by the rope minus the friction force, and when this net force exceeds the friction force, the object will start to accelerate according to F=ma. Therefore, although the force is increasing, the acceleration remains constant until the friction force is exceeded.
  • #1
blueberryfive
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Homework Statement



An object is at rest and stays at rest, but a rope attached to it is pulling with increasing force. What is the acceleration?

Homework Equations



F=ma

The Attempt at a Solution



The solution is that acceleration is constant and 0. Obviously a= dv/dt =0, since the object is at rest.

But if force is increasing, since F=ma, isn't acceleration increasing as well?

This is probably a stupid question, but I'm confused
 
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  • #2
Consider a block of wood on a table. As you gradually start pulling, or pushing, on the block, the force will obviously increase but the friction force will be equal to and opposite the force you are applying up to a maximum value. When the friction force is exceeded, then the block will accelerate according to F = ma where F is the net force on the block. The net force will be the force you are pulling with minus the friction force. Then there will be acceleration.
 
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  • #3
Thanks, so I guess my problem is that F is the net force, not just the pulling force applied to the block.
 
  • #4
That is correct.
 
  • #5
.

Your understanding is correct. As the force increases, the acceleration will also increase. However, since the object is initially at rest and remains at rest, the acceleration will still be 0. This is because there is an equal and opposite force acting on the object, balancing out the force of the rope and keeping the object in a state of equilibrium. So even though the force is increasing, the acceleration remains at 0 because there is no net force acting on the object. It is important to remember that the relationship between force and acceleration is not always linear and can be affected by other factors, such as the presence of other forces.
 

1. What is the relationship between force and acceleration in an object at rest?

In an object at rest, there is no acceleration. This means that the object's velocity is constant and it is not changing its position. Therefore, there is no relationship between force and acceleration in an object at rest.

2. Can an object at rest have a force acting on it?

Yes, an object at rest can have a force acting on it. This force is known as the net force and it is the sum of all the forces acting on the object. However, since the object is not moving, the net force must be zero in order for the object to remain at rest.

3. What happens to an object at rest when a force is applied to it?

If a force is applied to an object at rest, the object will start to accelerate. This is because the force causes a change in the object's state of motion, leading to a change in its velocity. The object will continue to accelerate until it reaches a new state of rest or until another force acts on it to change its velocity.

4. How does the mass of an object affect its acceleration in an object at rest?

The mass of an object does not affect its acceleration in an object at rest. This is because, as mentioned earlier, there is no acceleration in an object at rest. The mass of an object only comes into play when a force is applied to it, as it determines how much force is needed to accelerate the object.

5. Is it possible for an object to have a force acting on it and still be at rest?

Yes, it is possible for an object to have a force acting on it and still be at rest. This is because, as long as the net force on the object is zero, it will remain at rest. For example, if two equal and opposite forces are applied to an object, they will cancel each other out, resulting in a net force of zero and the object will remain at rest.

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