Force and Acceleration: Necessity of Force for Acceleration

In summary, the necessity of a force in relation to acceleration is rooted in Newton's laws, specifically the first law which states that an object will remain in motion unless acted upon by an outside force. Acceleration involves a change in kinetic energy, which requires work to be done on or by the object, thus, a force is necessary. However, it is important to be careful in using certain terms, as uniform circular motion involves acceleration but no change in kinetic energy. Additionally, the concept of 'why' questions may not always have a complete answer, but rather provide an explanation to help understand a phenomenon.
  • #1
Bashyboy
1,421
5
Why is it necessary that there has to be a force if there is an acceleration?
 
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  • #2
Remember Newton's laws - an object in motion will stay in motion until acted on by an outside force. So, an object will normally be in a state if uniform motion - moving with constant velocity. If you want to change this uniform motion (accelerate it), you need to apply an outside force.
 
  • #3
Acceleration implies a change in Kinetic Energy, that involves work being done on or by an object - which implies a force moving through a distance.

That isn't a true answer to "why" but there never is a complete answer to 'why' questions. All you can hope for is that an explanation helps you to put the unexplained thing in amongst enough familiar things that one is satisfied and it begins to make sense.
 
  • #4
You must be very careful about the terms you use.
Newtons first law states that an object will remain at rest or move with constant velocity (constant speed in a straight line) unless it experiences a RESULTANT (unbalanced)force. If there is a RESULTANT force then there will be an acceleration.
It is misleading to associate Kinetic energy with acceleration. Uniform circular motion involves acceleration but no change in Kinetic energy.
Change in momentum but not KE
 
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  • #5
Good point.
So change the argument by saying Momentum Change is equal to Force times Time. The K.E. argument only works for motion in a straight line. The work done during circular motion is zero because the force and motion are at right angles.
You really have to be on your toes on this forum!
But I still stand by my statement about 'why' questions.
 
  • #6
I am not going to be the one to 'change the argument'.
The original query was straight forward and the explanation is easy straightforward textbook stuff.
Changing the argument will result in yet another 50+ posts about nothing in particular.
 
  • #7
Because of inertia.
 

Related to Force and Acceleration: Necessity of Force for Acceleration

1. What is the relationship between force and acceleration?

The relationship between force and acceleration is described by Newton's Second Law of Motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This means that the greater the force applied to an object, the greater its acceleration will be.

2. Why is force necessary for acceleration?

Force is necessary for acceleration because it is what causes a change in an object's velocity. In order for an object to accelerate, there must be an unbalanced force acting on it. Without force, an object would either remain at rest or continue moving at a constant speed in a straight line.

3. Can an object accelerate without a force acting on it?

No, an object cannot accelerate without a force acting on it. This is because acceleration is a measure of the change in an object's velocity over time, and a force is required to cause this change. Without a force, there would be no change in velocity and therefore no acceleration.

4. How does the direction of the force affect acceleration?

The direction of the force affects acceleration because acceleration is a vector quantity, meaning it has both magnitude and direction. The direction of the force determines the direction of the acceleration. For example, if a force is applied in the same direction as the object's velocity, the object will accelerate in that direction. If the force is applied in the opposite direction, the object will decelerate or accelerate in the opposite direction.

5. What is the unit of measurement for force and acceleration?

The unit of measurement for force is the Newton (N), named after Sir Isaac Newton. The unit of measurement for acceleration is meters per second squared (m/s²). This means that for every second, the object's velocity will change by a certain amount of meters per second in the direction of the force.

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