Velocity doesn't even appear in Newton's second law.kq6up said:With my understanding of Newton's second -- if I am going to use it to solve a problem, I would need to write ALL velocities in the system with respect to the lab frame (inertial rest frame) -- correct?
What, you have there is acceleration and average acceleration, which of course can be expressed in terms of velocity.kq6up said:It does in the rocket problem. ##\dot{p}=\dot{m}v+m\dot{v}=F_{thrust}##. Also, if you are calculating the the change in momentum over some time interval ##F=m\frac{\Delta v}{\Delta t}##.
Newton's Second Law, also known as the Law of Acceleration, states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
The main assumptions in Newton's Second Law are that the object is a point mass, there are no external forces acting on the object, and the forces acting on the object are constant and in the same direction.
Considering the assumptions in Newton's Second Law is important because it helps us understand the limitations and scope of the law. It also allows us to make accurate predictions and interpretations of the law in different scenarios.
If the assumptions in Newton's Second Law are not met, the law may not accurately describe the motion of the object. For example, if there are external forces acting on the object, the net force acting on the object will not be equal to the mass times acceleration.
No, the assumptions in Newton's Second Law may not always be met in real-world situations. For example, objects are not always point masses and there are often external forces acting on them. However, the law still holds true in many cases and can still be a useful tool for understanding motion and making predictions.