Question

state Laws of Motion and reflection

Answer 1

To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.
If a teacher is going to insist that students memorize all three laws and regurgitate them on command, I'd at least recommend historical accuracy. But if you want to simplify, then I'll tell you how to do it.

First, we recognize that #2 above means F=ma, where "F" stands for the net force acting on an object (and both "m" and "a" are defined below). A force is often defined as simply a push or a pull, and that works for most conversations, but when teaching this topic at middle school or above I think we should define a force as an interaction between two objects that would tend to accelerate the objects. The term "net force" simply means that forces can combine, add together, and/or cancel one another out. The forces acting on an object need to be summed with vector addition before F=ma is used.

To continue, "m" stands for mass, which is a way to quantify inertia. Inertia is an object's tendency not to change it's state of motion. Things don't speed up, slow down, or change direction without something making them do so. Some things are more obstinate than others in this regard, and mass gives us a way to measure this quality in any object.

Lastly we note that "a" stands for acceleration, which is the rate of change of velocity. Acceleration is how quickly an object is speeding up, slowing down, or changing direction. Like force, acceleration is a vector quantity, which means that the quantity has a direction. Specifically, the acceleration of an object is in the exact same direction as the net force acting on the object. "F" and "a" are in bold font because that's shorthand to note that they are vectors.

These three paragraphs to describe the equation F=ma are covered by every physics teacher and physical science teacher around the world. That's certainly not my complaint. My point is that Newton's First Law is unnecessary if you actually understand the equation for Newton's Second Law. The First Law is just telling us that when the left side of F=ma is zero, so is the right. In Newton's day, this was a major insight--he was basically pointing out to people that Galileo was correct about inertia, and Aristotle was not. I find that my students are unfamiliar enough with Aristotle that I don't need to address the misconception as a separate lesson--it's just part of the Second Law lesson.

Having done away with the need for the First Law as a separate lesson, allow me to point out that the Third Law doesn't need a separate lesson, either. It is covered by our definitions. Since a force is an interaction between two objects that would tend to accelerate the objects, I need only remind students that the Second Law will apply to both objects experiencing the force in question. Done. Again, in Newton's day it was necessary to state this as a separate concept, because action at a distance (without contact, as in gravitational forces or electromagnetic forces) was not well understood. As with the First Law, the Third addresses a misconception that my students simply don't have.

To summarize, Isaac Newton gave us a single law of motion that works helps us to predict the motion of any object we might study in AP Physics and equivalent college courses. This Law does fail to explain quantum mechanics and relativity, but it has us covered up until those topics, both of which are beyond the scope of our course and our everyday lives. For any problem we have, F=ma, and that's all there is to memorize

Answer 2

Answer࿐

Laws of reflection:-

1st law:-The incident ray, the reflected ray,and the normal at the point of incidence lie on the same plane.

2nd law:- The angle of incidence is equal to the angle of reflection.