# Need help elaborating different physics concepts in these statements

## Homework Statement

I have an oratorical exam, with two of these statements given randomly. So I have to give at least 5 minutes of elaboration of each statement.

1. A force is something capable of changing an object’s state of motion. To produce a change in motion, there must be a net or unbalanced force.

2. Friction is the resistance to motion that occurs between contacting surfaces. The frictional force between surfaces is characterized by coefficients of friction.

3. The total energy of the universe or of an isolated system is conserved. The total mechanical energy is constant in a conservative system.

4. In the absence of a net external force, the total linear momentum of a system is conserved. Momentum is conserved in both elastic and inelastic collisions.

5. Mechanical equilibrium requires that the summation of forces and the summation of torques are both equal to zero.

6. An object will float or sink in a fluid depending on the ratio of its density with the density of the fluid. Also, an object fully or partially submerged in a fluid is buoyed up by a force equal in magnitude to the weight of the volume of fluid it displaces.

7. The electric field is a vector field that describes how nearby charges modify the space around them.

8. Electric current is the net rate at which charge flows past a given point. Electrical resistance of circuit element depends on its geometry as well as the intrinsic electrical properties of its material.

9. A transformer is a device that changes the voltage supplied to it by means of induction. If the voltage is increased, the output current is reduced, and vice versa.

10. The Law of Reflection: the angle of incidence equals the angle of reflection. The angle of refraction is given by Snell’s Law.

## Homework Equations

Usage of formulas would be helpful in proving these statements but I can tell you minimal mathematical computations are needed here.

## The Attempt at a Solution

Again, its entirely oratorical, the only solutions I need are those that would help support my statements in elaboration of these concepts.

## Answers and Replies

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kuruman
Homework Helper
Gold Member
Is there a specific question that you wish to ask or do you expect someone to provide you with ten five-minute elaborations on each subject?

Umm, no. I could elaborate it on my own. What I would need exactly is what law/physics concept at work here.

Like
1. Newton's Second Law / Law of Inertia (I get jumbled up here)
2. Kinetic Friction
3. Law of Conservation of Energy

And so on.