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High School Physical Science—Semester B

Physical is as physical does.

  • Course Length: 18 weeks
  • Course Type: Basic
  • Category:
    • Science
    • High School

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Behold, Semester B of physical science. This is the really physical bit of physical science. Now that we've vanquished any fears about the properties of matter, atoms, chemical bonds, organic chemistry, and radiation, it's time to put the world into motion. This time, we'll explore the laws that govern everything from Labradoodles on skateboards to rocket ships.

While physical science Semester A focused on topics studied by chemists, physical science Semester B focuses on topics studied by physicists. This course guides you through everything from motion to waves, and all the cool ways in which we take advantage of our understanding of the physical world. Think: smartphones and egg-protecting devices.

Instead of just reading about it all, this course provides many, many activities to put your knowledge into action, enough practice problems to put your knowledge to the test, and gobs and gobs of examples to build up your knowledge to help you rule the world.

Well, you might not rule the world, but at least you'll attract admiration from your friends and fear from your enemies, which is the next best thing.

In this course we'll discuss:

  • How and why things move
  • Forces throughout the universe
  • What's up with energy, where it comes from and where it goes when people aren't looking
  • How come work is the best thing ever and how we can use it to our advantage
  • Why electricity and magnetism are closer than BFFs who finish each other's sentences, and how we can use both electricity and magnetism to create the circuits that run our world
  • How waves travel, bump against things, and affect those things by bumping into them

So grab a Labradoodle and a skateboard, grab a pencil and a pocket calculator, and don't forget a poodle-friendly helmet. Then step into Semester B of physical science à la Shmoop. (No poodles will be harmed in the completion of this course.)

P.S. physical science is a two-semester course. This is the second semester. Find the first semester here.

Technology Requirements

From a technology standpoint, all you need for this course is a web browser-capable computer and a reliable internet connection. A tablet works, too, if you don't mind typing on it. Additionally, access to a scanner or digital camera, or a cellphone with a camera, or jeez, even a webcam, will come in handy, since you'll occasionally need to upload images of diagrams you draw. That's it.

Required Skills

Knowledge of basic Algebra

Unit Breakdown

9 High School Physical Science—Semester B - Motion

Physics is the subject of Sir Isaac Newton, Albert Einstein, and Stephen Hawking. It's definitely smarty-pants territory, but that doesn't mean we can't learn a lot of it ourselves. At its heart, physics tries to explain the basic laws that make the universe tick. Unfortunately, the universe is a lot more complicated than a clock, but don't worry—we'll take things slow.

We start by talking about the most basic topic in physics: motion. If we're going to figure out why things move, we first need to be able to measure how they're moving. We'll look at distance, speed, and acceleration and see how objects fall when we drop them off the leaning tower of Pisa. And, yes, there will be a bit of math. Nothing to fear, though. Keep moving and you'll be good to go.

10 High School Physical Science—Semester B - Forces

"Use the force, Shmooper." 

Yeah, talk about not helpful advice. Well, that advice isn't helpful yet. It will be after we complete this unit and learn how forces work. If motion was about how things move, forces are about why they move. That goes for our bodies, cars, falling objects, and even the particles deep inside our bodies. When they say that physics is the science of everything, they weren't kiddin'. We'll look at the various forces that make the world go around. We'll also check out some laws to explain how they work, paying special attention to gravity, and consider the forces that act on objects in circular motion (think: astronauts in the International Space Station). If anyone harbors a secret desire to be an astronaut, now is the time to listen carefully.

11 High School Physical Science—Semester B - Energy and Momentum

A universe without energy or momentum would be a depressing place: it would be dark, very dark, and there would be no light, no particles, no sound, no nuthin'. Luckily for us, that's not the case. Some days it might feel like we have no energy or momentum, but the truth is we still have gobs of it. Energy is particularly important—it's how our bodies continue to live. Thanks, energy.

In the first half of this unit, we'll learn what energy is, how it works, and how it moves. Then, we'll move on to momentum and use our new knowledge to figure out how to protect a poor, defenseless egg.

12 High School Physical Science—Semester B - Work, Power, and Machines

Nobody likes work. That is, until they realize that even playing video games counts as "work." That's because work in physics means something a little different than work in everyday life. In this unit, we'll learn what work really is and how our knowledge of work can help us build all kinds of useful contraptions. Before we know it, we'll be building devices like Inspector Gadget and lifting large objects with the power of mechanical advantage. When we understand physics, it's amazing what we can do.

13 High School Physical Science—Semester B - Electromagnetism

Don't tell anyone, but electricity and magnetism are really the same thing. Shh! Sure, we might have come across the topics before and no one probably mentioned the connection, but it's time to face the truth. And it's a pretty cool truth, because it allows us to charge iPhones, store energy, power cities, diagnose disease, and perhaps most importantly, talk about magnets and static electricity in the same unit. Whether it's magnets or charges, opposites attract, and both can produce some powerful forces—forces we'll be studying in this unit.

14 High School Physical Science—Semester B - Circuits

If you've ever run a circuit on a track, you have a pretty good idea about how electrons must feel. A circuit is a bunch of electrons running a 4K, carrying energy and moving close to the speed of light. That's why it's called a circuit. We love our cell phones, computers, and electric lights, and without electricity, none of them would do a thing. So, if we're going to understand our modern, high-tech lives, we need to explore circuits.

Circuits run on electricity—the movement of the same charges we talked about last unit. But solving problems with circuits runs on brain power (which also runs on electricity, but that's for a biology class to go into). We'll build up the brain power to solve any circuit problem through a lot of practice, so get ready because here. we. come.

15 High School Physical Science—Semester B - Waves

Waves, like life, are full of ups and downs. They come in many different types: sound waves when our little brother screams at the top of his lungs, light waves when we watch our favorite TV show, and water waves when we're paddling at the beach. In this unit, we'll learn about all of these and more. We'll even figure out why you don't need to be scared of microwaves, and why your cell phone doesn't cause cancer: all through the physics of waves.

16 High School Physical Science—Semester B - Final Exam

We will review each unit and work on practice problems to prepare for the final exam. After reviewing the content, we'll also work on some problem-solving skills, how to recognize problem types, and work towards the correct solution. You got this.

Recommended prerequisites:

  • Algebra I—Semester A
  • Algebra I—Semester B
  • High School Physical Science—Semester A

    • Sample Lesson - Introduction

    Lesson 12.03: Simple Machines

    Complex 1930s envelope-making machines.
    Machines don't have to look like this.
    (Source)

    Machines come in all shapes and sizes. We have food processors, washing machines, ramps, cars, and those strings that adjust the blinds. With so much to talk about, that's why we need to keep things simple. In this lesson, we're going to talk about simple machines.

    When we say simple, we really do mean simple. We're not talking about an entire car, but we might be talking about the wheels and axle. We're not talking about an entire chest of drawers, but we might discuss the screws that hold each part together.

    What we're really talking about when we discuss simple machines are the basic parts that can be put together to create all kinds of weird and wonderful contraptions. The various bits that go into a Rube Goldberg device, or the cogs, pulleys, and belts that make a robotic production line do its thing. Each one of those parts might be simple, but it's also a work of human ingenuity.

    Some machines can be very complex, but don't worry, we'll keep things nice and simple. We don't call 'em simple machines for nothin'.

    Sample Lesson - Reading

    Reading 12.12.03: Don't Be So Mechanical

    We tend to think of machines as being big, sprawling, complicated contraptions. We think of production lines and tumble dryers and things like that. But machines can be incredibly simple. When humans invented the wheel, they invented one of the very first machines. Or when we wedge a door open with one of those little wooden blocks, we're using a machine.

    A machine is just something that creates, transfers, or adjusts forces or movement. Most machines are automated, but they don't have to be.

    Simple machines are particularly…well, simple. A simple machine is a basic device that can change the direction of a force or the size (magnitude) of that force. Archimedes is particularly famous for studying simple machines and highlighting three machines that existed in his time.

    From then until the Renaissance, humans came up with three more. Together these form the six classical simple machines. They are:

    • Levers
    • Pulleys
    • Wheels
    • Wedges
    • Inclined planes (slopes)
    • Screws

    In this lesson, we'll go through each of them and explain how they work in terms of physics. We'll also explore how we can use them to build contraptions and solve problems.

    Levers: Moving the World

    The first part of this lesson is pretty much all about seesaws. Maybe we should take a field trip to the park.

    A lever is basically just a straight, rigid material that is put over a rigid pivot point (or fulcrum). By doing this, we can multiply the size of the force we apply. We can apply a small force at the long end of the lever to create a bigger force at the short end of the lever.

    Three examples of levers in action.
    Humans, being the brainy beasts we are, have figured multiple ways to use levers.
    (Source)

    Let's say we have a 6-m-long seesaw, with a pivot 2 m from the right-hand side. If our friend, who weighs 45 kg (which has a force of gravity of 441 N) gets on at the short end, how much of a force at the other end will it take to balance the seesaw? Here's our see-saw, with all the distances and forces marked:

    With seesaws (and levers in general), the relationship we need is:

    F1d1 = F2d2

    The d variables are how far each force is from the pivot point.

    F1 × 4 m = 441 N × 2 m

    Then we could solve the equation to find the force needed:

    This "Fd" combination of variables has a special name: torque. Torque is a force that turns things in either a clockwise or counter-clockwise direction. We usually write it with the Greek letter Τ, which is pronounced "tau."

    The equation for torque, Τ = Fd, might be a little bit confusing, because it kind of looks like the equation for work. But don't get confused. The distance here is the "perpendicular distance" from the fulcrum to the point where the force is being applied. It isn't the displacement of the object itself, and unlike with the work equation, the force and distance are at 90° angles to each other. With work, the force and displacement always had to be in the same direction. So, they're totally different things.

    Got levers? Great. We've got 5 more simple machines to go.

    Pulleys: Closing the Drapes

    A simple pulley: a rope strung over a wheel with weights on both ends of the rope.
    (Source)

    Where levers are about the size of force, pulleys are more about the direction. A pulley is just a wheel with grooves around the edges, letting us run a rope or string across it. They can be super useful. Like when we're trying to haul rope on one of those old-fashioned tall ships, which we do all of the time.

    Let's say we need to pull a rope down, straight towards the poop deck we're standing on (no jokes because we're not five years old). Pulling down on a rope can actually be quite hard to do.

    Let's say we need six people to pull the rope at the same time. Where are those six people going to stand? There isn't room for everyone to grip the rope. So instead, we could run the rope over a pulley, and then move the length of rope horizontally along the deck instead. Then six people can get in a line and pull the rope together. Being able to change the direction of a rope like this can make the impossible possible.

    Although pulleys are mostly a matter of direction, we can also use pulleys to multiply forces just like with a lever. By running a rope over several pulleys, we can multiply our force as many times as we need. It basically creates multiple tension forces that work together to pull the thing we're trying to pull. That way we don't have to pull as hard. The downside is that we need to pull for a lot farther, but that's totally worth it if it makes us look like the Hulk.

    A rope wound through a system made of multiple pulleys.
    (Source)

    (Sweet) Wheels

    It's always an exciting day when we get ourselves some sweet wheels. Whether it's an energy-efficient hatchback, a convertible, or an SUV, it's always exciting. It's hard to miss how cars have completely changed society, but maybe the biggest change is with the wheels themselves.

    A wheel combined with an axle—a rod stuck in the middle of the wheel—is a simple machine that's been around since the days of chariot racing. In modern cars, the axle rotates and causes the wheel to rotate along with it, transferring the force. In other wheel-and-axle combos, the wheel is what turns, transferring the force to the axle. Either way, we're taking our force for a spin in a new direction.

    A rope with a bucket on the end is wrapped around a large axle. By spinning the wheel, the bucket will move up or down.
    A windlass uses the concept of the wheel as a simple machine.
    (Source)

    Like with pulleys and levers, we can even use wheels to increase or decrease a force. By attaching wheels and axles of different sizes together, we can make it easier or harder to move stuff around. Pretty useful. If we count gears as a type of wheel, the possibilities for this simple machine are endless.

    Slopes: It's All Downhill from Here

    A box rests at an angle on a sloped surface.
    A free body diagram of an inclined plane in action.
    (Source)

    Whether we call them inclined planes or slopes, they work the same way. It might seem strange to call a slope a machine, but it does basically the same thing as many of the other machines we've talked about.

    When professional movers come to move someone's stuff to a new home, they use a ramp to get things in and out of their moving van. It takes just as much energy to lift something in or out of the van, whether we use a slope or lift it straight up. So, why bother with the ramp?

    Well, like with a lever, wheel, or any other simple machine, it's about force. It takes less force to move a grand piano up a slope than it does to lift it straight up like an elevator. Where we lose is distance. Lifting straight up is a smaller distance than going diagonally, but going diagonally means we don't have to exert as much force at any given moment. When we're talking super heavy stuff, our muscles will thank us for using the slope.

    Wedging Knowledge in Our Minds

    We're going to level with you. Although wedges are considered to be one of the big six simple machines, they're pretty much just tiny slopes. The only difference with a wedge is that we can use it to jam two things together. Slopes are used to move things from one place to another, while wedges are used to separate two objects, hold things in place, and transfer forces. Any force applied to the flat end of the wedge will turn into a diagonal force pointed up and away from the slope.

    A triangular wedge is jammed in a piece of wood. A hammer strikes the flat edge of a wedge, transferring the downwards force sideways into the wood.

    Think about tools and weapons like axes, arrows, or spears. Back in the Stone Age, we'd create our arrowheads and blades from stone that was shaped like a wedge. Then, when we hit a log with the tool, our forwards force would help split the log apart. The wedge converts the forwards force into a sideways force.

    Not Having a Screw Loose

    A simple screw.
    (Source)

    Last of all is the trusty screw. Where would we be without screws to hold practically our entire home and all its furniture together? Screws convert a turning force (us turning the screwdriver) into a forwards force as it drives through the material. It super simple, but pretty ingenious.

    That's a Wrap

    All right, and that's all six simple machines. Know 'em and love 'em, because they're super handy to have around.

    Sample Lesson - Activity

    1. Which of the following statements about machines is true?

    2. Which of the following isn't a simple machine?

    3. Which of the machines below uses a fulcrum to help get its job done?

    4. True or false: The fulcrum of a machine always has to be located between the force and the load.

    5. Which statement below about pulleys is false?

    6. What are three examples of wheels being used as simple machines? Give examples that aren't the wheels on vehicles, carts, or chairs (since we want you to be a little more creative with your answer than that).

    7. Which statement below about inclined planes is false?

    8. Which of the following isn't an example of a wedge?

    9. Which of the following simple machines both changes the direction of force and multiplies it as well?

    10. How are work and torque related to each other?

    11. Derrick Shmoop (70 kg) takes his daughter Tisha (35 kg) to the playground to ride the seesaw. Tisha sits on one end of the 6-m long seesaw. The fulcrum is in the middle of the seesaw. To get the seesaw to balance, the torques have to be equal; otherwise one person just sits on the ground and the other sits up in the air, and nothing happens. Where should Derrick sit to make the seesaw work? Hint: g = 9.8 m/s/s

      A box, labeled '35 kg', sits at one end of a six-meter line. A fulcrum is placed beneath the line's midpoint.

    Sample Lesson - Activity

    1. Which of the following is not a simple machine?

    2. What do simple machines do for us?

    3. Jimmy Neutron, a boy genius, likes to experiment with, well, everything. Including seesaws. He created a seesaw with an unbreakable adamantium bar 20 m in length sitting on a fulcrum that is 5 m from one end and 15 m from the other end. If Jimmy had his friend Sheen (who has a mass of 30 kg) sit on the end 15 m from the fulcrum, how much mass would Jimmy need to put on the short end (5 m from the fulcrum) to exactly balance the seesaw and keep it perfectly horizontal?

    4. When we use a ramp (an inclined plane) to move a box up onto a truck, for example, we make a tradeoff between using a smaller force to accomplish the job and __________.

    5. Which of the following simple machines does not multiply forces?