Pulse-width modulation is a technique that allows a microcontroller to control the speed of motors, brightness of LEDs, or average voltage without needing a DAC.
If you don't have a microcontroller with on-board PWM hardware, or have run out of PWM channels, how can PWM be simulated using software?

An object is accelerated at a constant 70m/s/s from the ground through a height of 2m. What is the object's maximum height, time to maximum height, velocity upon hitting the ground, and total time in the air?

An object experiences an acceleration of -4m/s/s for a period of 2.5s, after which the object has a velocity of 0m/s. What is the object's initial velocity and how far does it travel during the acceleration?

An object 2m above the ground has an initial vertical velocity of 15m/s. How long does it take to reach maximum height, and what is the maximum height? What is its velocity when it hits the ground? What is its total time in the air?

A process in a factory requires molten metal be dropped from a height and remain in freefall long enough to harden before impact. If the time needed to harden is 4s, how high must the molten metal be dropped from? What is the metal's velocity when it hits the factory floor?

A hockey puck is moving over the ice at 8m/s when it hits a rough patch of ice 5m in width. The puck continues on smooth ice at 6m/s. What was the puck's acceleration through the patch of rough ice? How long was it moving through the rough ice patch?

If an aircraft's velocity is 300m/s when the pilot increases the throttles to 100%, what is its acceleration if the final velocity is 400m/s and the distance covered is 4km? How long did it take for the aircraft's velocity to increase 100m/s?

Suppose the plates of a capacitor are separated by 1.7cm and are oppositely charged. A proton is released on the surface of the positively charged plate and collides with the negatively charged plate 1.57us later. What is the strength of the electric field, and what is the proton's velocity when it hits the negatively charged plate?

How does an atom get its color? It all comes down to an atom's electronic configuration, that is, the number of electrons the atom contains.
Basic atomic structure:
Movement between electron orbits:

How can we use the light emitted by an object to figure out the composition of said object? We can do so by splitting light emitted by the object into its constituent components, then by comparing the results to "fingerprints" of chemical elements. This is called spectroscopy.

Can electrons move from one orbit to another? If so, is energy consumed or emitted during the move? Let's quickly examine electrostatic charge and Coulomb's law to find out.

What are the parts of an atom and where do they reside within an atom? What is their mass? Do they have electric charges? Let's take a brief look at the Bohr model to find out the answers to these questions.

Suppose there are two points in space where electric potential has been measured. Point A, at -1m, measures -1000V. Point B, at 1m, measures 1000V. What is the electric field, in V/m?

Suppose we have an electric field of 3000V/m. What is the potential between a point at 10cm and a point at 30cm?

Suppose there exists two plates with a space between them of 1.8cm and an electric field of 51000N/C. If a proton is released on the surface of the positive plate, what is its velocity when it hits the negatively charged plate?

Suppose we have a proton and some point 0.053nm from the proton. What is the electric potential at said point? Now suppose there is an electron at this point. What is the potential energy of this electron?

What would a #SpaceForce look like? The answer is probably a lot like what we already have.

Suppose there is a container with a piston that can be moved to increase or decrease the container's volume. Inside this container is a gas at a pressure of 1,500,000Pa and temperature of 200C. The initial volume within the container is 0.025m^3. The piston is moved out of the container until the pressure is 950,000Pa. What is the final volume of the container?

Just one thing I noticed with many conversations about the de-platforming of Alex Jones/#InfoWars. There seems to be confusion, and in some cases purposeful ignorance/stupidity/deception, regarding the difference between the term "public" when used to mean a government, and "public" when used to describe a company.

Suppose a bag is filled with a gas until the bag's volume reaches 22.4L. The temperature and pressure of the gas within the bag remain constant at 20C and 1atm respectively. How much gas has been introduced into the bag by the time its volume has reached 22.4L?

What is the difference between nuclear fusion and nuclear fission?

Phys in 4 is a series of instructional videos in which concepts from physics and chemistry are explained in less time than it takes to create a video that is 4GB in length.

Is there a difference between centripetal acceleration and centripetal force, and if so, what is it? If we know the mass of an object moving along a curved path, how can we calculate the centripetal acceleration and/or force?

In this Problems with Physics, we take a look at two trucks having the same momentum but different masses. When the two trucks stop at a light, which truck's braking system does more work?


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