Physics Chapter 11: Motion and Distance

Study Notes

To describe motion completely, we need to know the distance, displacement, speed, velocity, and acceleration of an object.
The SI unit for distance is meters (m), and other units that can be used include kilometers (km), centimeters (cm), and miles (mi).
Distance and displacement are different, with distance being the total length of the path traveled and displacement being the shortest distance between the initial and final positions.
Displacement is a vector quantity, and adding displacements requires the use of vector addition.
Pythagorean's theorem is used to find the magnitude of the resultant vector in vector addition.

The slope of a distance-time graph represents the speed of an object.
A straight line with a positive or negative slope represents an object moving at a constant speed.
A line that curves upward or downward represents an object undergoing acceleration or deceleration.
A horizontal line represents an object at rest.

Instantaneous speed and average speed are different, with instantaneous speed being the speed at a particular instant and average speed being the total distance traveled divided by the time taken.
The SI unit for speed is meters per second (m/s), and other units that can be used include kilometers per hour (km/h) and miles per hour (mi/h).
Speed and velocity are different, with speed being a scalar quantity and velocity being a vector quantity.
The average speed equation is used to find the average speed of an object over a certain time period.

Acceleration is the rate of change of velocity, and it is measured in meters per second squared (m/s²).
A speed-time graph indicates acceleration when the slope of the graph is not zero.
Instantaneous acceleration is the acceleration at a particular instant.
Acceleration can be negative, indicating a decrease in velocity.

A force is a push or pull that affects the motion of an object.
The four main types of friction are static friction, kinetic friction, rolling friction, and fluid friction.
Gravity and air resistance are forces that affect the motion of a falling object, with gravity acting downward and air resistance acting upward.
Newton's first law relates a change in motion to a zero net force.
Newton's second law relates force, mass, and acceleration, with the equation F = ma.

Momentum is the product of an object's mass and velocity.
Momentum is conserved, meaning that the total momentum of a closed system remains constant.
Newton's third law of motion states that every action has an equal and opposite reaction.

A force does work when it causes an object to move through a distance.
The SI unit for work is the joule (J).
Work and energy are related, with work being the transfer of energy from one object to another.
Power is the rate of doing work, and it is measured in watts (W).
One horsepower is equal to 746 watts.
Machines can do work through three ways: by changing the direction of the force, by changing the magnitude of the force, or by changing the distance over which the force is applied.

The six types of simple machines are levers, pulleys, wheels and axles, inclined planes, wedges, and screws.
A lever is a type of machine that consists of a rigid bar pivoted at a fixed point.
The mechanical advantage of a machine is determined by its ability to change the direction or magnitude of the force.
Two or more simple machines make up a compound machine.

Energy is the ability to do work, and it is measured in joules (J).
Work and energy have the same units because they are related.
Kinetic energy is the energy of motion, and it depends on the mass and velocity of an object.
Potential energy is the energy of position or stored energy, and it depends on the mass and height of an object.
The major forms of energy include thermal, kinetic, potential, electrical, chemical, and nuclear energy.
Energy can be converted from one form to another, but it cannot be created or destroyed.
The law of conservation of energy states that the total energy of a closed system remains constant.
Energy conversion takes place when an object falls to earth, with potential energy being converted to kinetic energy.
Mass and energy are related, with mass being converted to energy according to the equation E = mc².
The major nonrenewable and renewable sources of energy include fossil fuels, nuclear energy, solar energy, wind energy, and hydro energy.
Energy conservation is the practice of reducing energy consumption, and it is important because it helps to reduce the depletion of energy resources and mitigate environmental pollution.