Trouble understanding Newtons first law and f=ma

[zsawyer]

In reading Newtons first law,
An object at rest or in motion will remain the same unless acted on by an outside force.

also known and understood in Newtons 2nd is
Force = mass x acceleration.

An object "A" moving at a constant velocity has no acceleration therefor no force.
Object "B" is stationary. When object A hits object B, B will cease to be stationary.

Where did the force to move object B come from if A has no force?

 

[Sakha]

Actually Newton's 2nd law is F=dp/t (change in momentum over time), so object A has mommentum, and loses some which is given to B.

 

[cjl]

In reading Newtons first law,
An object at rest or in motion will remain the same unless acted on by an outside force.

also known and understood in Newtons 2nd is
Force = mass x acceleration.

An object "A" moving at a constant velocity has no acceleration therefor no force.
Object "B" is stationary. When object A hits object B, B will cease to be stationary.

Where did the force to move object B come from if A has no force?

Force isn't an inherent property of an object. That's your error - your statement that "An object 'A' moving at a constant velocity has no acceleration therefore no force" sounds like you are assuming that an object can have an inherent "force" that it can transmit to other objects.

In your example, while object A is moving at a constant velocity, there are no forces acting on it, but when it hits object B, there is definitely a force that occurs at impact, which serves to both slow down object A and accelerate object B. The exact details of the collision are somewhat complicated, depending on the properties of each object, but there is definitely a force that occurs between them at impact.

 

[zsawyer]

Your what I could not quite manifest in my mind. Thanks.

Got it. Newtons laws are best explained in terms of momentum, some reason F = ma sticks out more in high school text. Force is not an inherent property.

 

[sardar]

Newton's first law states that an object at rest or in motion will remain in that state unless acted upon by an external force. This means that an object will continue to move at a constant velocity or remain at rest unless a force is applied to it. In the case of object A and B, object A is already in motion and does not require an external force to keep it moving at a constant velocity. However, when it collides with object B, it exerts a force on B which causes B to move. This force is the result of the acceleration of object A, as described by Newton's second law: force equals mass times acceleration (F=ma). In this scenario, the force that moves object B comes from the acceleration of object A, even though object A itself does not experience a change in velocity. This is because the force is transferred from object A to object B upon collision. Therefore, Newton's first law and second law are both applicable in this situation and work together to explain the motion of the objects involved.