Unit of Work and Energy; Newton's Laws (Video Notes)

Vocabulary flashcards covering key terms from the lecture notes on work, energy, energy forms, and Newton's laws.

Work

The energy transferred to or from an object by the application of force along a displacement.

Displacement

The straight-line distance and direction through which an object moves when a force is applied.

Force

A push or pull that can cause motion or change in shape.

Joule

The SI unit of work and energy.

Newton (unit of force)

The unit of force; 1 N = 1 kg·m/s².

Energy

The ability to do work; can be transformed from one form to another but is conserved overall.

Kinetic Energy (KE)

Energy of motion.

Potential Energy (PE)

Stored energy due to position.

Chemical Energy

Energy stored in chemical bonds; can be transformed into other forms such as KE, electrical energy, or heat.

Electrical Energy

Energy from electric charges in motion.

Thermal Energy

Energy related to temperature; often expressed as heat.

Conservation of Energy

Energy cannot be created or destroyed, only transformed from one form to another.

Pendulum (energy transfer)

In a swinging pendulum, energy continually converts between potential and kinetic energy.

Newton's First Law (Law of Inertia)

An object at rest stays at rest and an object in motion stays in motion unless acted on by a net external force.

Newton's Second Law

F = ma; the net force on an object equals its mass times its acceleration.

Newton's Third Law

For every action, there is an equal and opposite reaction.

Inertia

The resistance of any object to a change in its state of motion or rest.

Mechanical Advantage

The measure of the force amplification achieved by using a tool, device, or machine.

Work Formula

W = F × d; work equals force multiplied by displacement in the direction of the force.

What is Ideal Mechanical Advantage (IMA)

The ratio of the input distance to the output distance of a machine without any energy losses due to friction

What is Actual Mechanical Advantage (AMA)?

The ratio of the output force to the input force in a real-world machine considering energy losses due to friction

Efficiency in machines

It's the ratio of useful output to total input, often shown as a percentage. For machines, it's how well they convert input energy into useful work, minimizing energy loss. Since some energy is always lost due to friction, heat, and other factors it’s always less than 100%

Coefficient of Fricton

The coefficient of friction (\mu) is a number that tells you how much friction there is between two surfaces.

Lever Formula and Basics

A lever is used to amplify force or change its direction, making work easier. Its components are a rigid bar (the lever) which rests on a fixed point called the fulcrum. An effort (the input force) is applied to move a load (the weight)

Formula: (force applied to lever) x (the distance from the fulcrum to where the effort is applied) = (the weight) x (the distance from the fulcrum to the weight)

Pulley

It consists of a grooved wheel and a rope/cable. Its core function is to redirect or multiply the force applied to lift or move heavy objects. It’s used to make work easier by changing the magnitude or direction of a force.

What is an inclined plane and how is its mechanical advantage

An inclined plane is a simple machine consisting of a flat, sloped surface that allows an object to be moved from a lower to a higher elevation with less force than lifting it directly. It increases the distance over which the force is applied, thereby reducing the required effort force.
The formula for calculating the ideal mechanical advantage (IMA) of an inclined plane is:
IMA = \frac{\text{Length of Incline (L)}}{\text{Height of Incline (h)}}

What is a wheel and axle and how is its mechanical advantage?

A wheel and axle is a simple machine made of two connected circles, a larger wheel and a smaller axle, that spin together around the same center. It helps you do work by making it easier to turn things or move heavy objects, like turning a doorknob or steering a car. The ideal mechanical advantage (IMA) tells you how much easier it makes the work. You find it using this formula:
IMA = \frac{\text{Radius of Wheel (R)}}{\text{Radius of Axle (r)}}

What is a wedge, how does it work, and what

A wedge is a simple machine that consists of two inclined planes joined back-to-back, tapering to a sharp edge or point. It is used to split, separate, or hold objects.

How it works:

When force is applied to the blunt end of the wedge, the force is amplified and redirected perpendicularly by the sloped sides into the object, causing it to split or separate.

Formula for Mechanical Advantage (MA):

The ideal mechanical advantage (IMA) of a wedge is calculated by dividing its length by its width:
IMA = {L \over W}
Where:

• L = length of the wedge (along the slope)
• W = width or thickness of the wedge (at its widest point)

Examples of wedges:

• Knives
• Axes
• Chisels
• Doorstops