Constructive and Destructive Waves

We're learning about sound now as our last unit. Today, I will be talking about constructive vs destructive interference waves.

Constructive waves are when two positive waves collide with each other to create a larger amplitude.

Destructive waves are when two negative waves collide with each other to create a smaller amplitude. If the waves are at the right amplitudes, they can cancel each other out in the aftermath of the collision.

Since larger amplitudes have higher sound volume, constructive waves make sound  louder than destructive waves.

Energy in Different Forms

There are many forms of energy in the world. Today, i will talk about some of these types of energy.

Chemical Potential Energy:
This energy involves atoms and molecules. Chemical bonds form within these molecules. In other words, objects that do work from fuels have chemical potential energy. For example, a car has chemical potential energy from the gas it has within it.

Mechanical Kinetic Energy:
Before I get into mechanical kinetic energy, we need to know what mechanical energy is first. Take a strongman lifting weights in the gym. As he is lifting them up, he is doing work. When an object does work, they are using mechanical energy. So what is mechanical kinetic energy? That's the energy the object with mechanical energy transfers to the other object, causing it to have a displacement. This object has now moved, and whenever an object is said to be moving, it has kinetic energy.

Gravitational Potential Energy:
This is the energy any object has because they are on Earth. Earth's gravity pulls down the object, causing it to have gravitational potential energy.

 Elastic Potential Energy:
This energy involves elastic objects such as slingshots  and bows. When a projectile is placed on the string of these objects, and the string is pulled back, the tension in the string builds up. When the string is let go, all that elastic potential energy is transferred onto the projectile, launching it forward.

Thermal Energy:
This is energy that deals with heat and temperature.

Sound Energy:
Energy that involves vibrations from an object.

CANNONS

We built cannons last week and today we finally fired them. Our materials that we had to bring were: 5 pop cans, 2 styrofoam cups, duct tape, and a can opener. The cannon is built with 3 cans and the base is built with 2. The goal is to get as much distance as possible on the x axes. In order to acheive that, we built our cannon at a 45 degree angle.  Our cannon was able to get the furthest distance in the class, at 260 m. It also caught on fire from the hole XD. But Jonathan reconstructed it, Good job Johnny!

4 Newton Problems

For all of these four problems, break them down to a FBD with x and y axes and set your positive axes.

Equilibrium:
This is when the object isn't moving and all the forces are equal to each other. The object is usually hanged up by two strings or beams. Using trig will find the unknown angle or side, depending on which is given.

Inclines:
This is where you have a slanted surface and an object at the top of that surface. There is a friction force acting on the object as it slides down the slanted surface. the equation for friction is mu*fn. The FBD has to be shifted a bit in terms of x and y.

Pulleys:
There are 2 FBDs for these types of problems, one for each object on the 2 ends of the pulley. We assume there's no friction and tension is the same for both sides.

Trains:
These are similar to pulleys. You still need 2 or more FBDs, depending on how many cars you have on the train. When your trying to find the acceleration, draw a FBD of the whole system. Friction is included in this problem. To solve for tension, you have to find each individual tension between each 2 cars.

Projectile Motion

There are 4 types of projectile motion questions. For all 4 types, we use the big five to solve them.
Type 1:
x:                             y:


ax = 0                      ay = gravity = 9.8m/s^2

vx is constant           vy = 0

dx = (vx)(tx)            dy = height

Time is equal for both x and y

Type 2:
x:                                   y:


ax = 0                            ay = gravity = 9.8m/s^2

vx = v1cos(θ)                vy = v1sin(θ)

dx = Range                    dy = 0

Time is equal for both x and y

Type 3 & 4:
These two are similar to Type 2. The only difference is that Type 3 has a positive dy and Type 4 has a negative dy.

Rollercoasters

We're building rollercoasters for our summative. Each group has about 4 people. It's gonna be very interesting to see what the final outcome of our rollercoaster to look like, I can't wait! Some of my favourite rollercoasters I've seen from past years are the mario speedway and the iron man coaster

How to Add Vectors

When presented with various vectors, and we're asked to add them up, how do we do it? Do we just add the length of the displacements together? If only it were that simple...

Here are the steps on how to add vectors.

1.) First, look at the equation given to you. If there are negatives (eg A - B), change it around so that it's adding the negative (eg A + (-B)). The negative only affects the direction of the vector, not the value. So if B was going East, negative B will be going West.

2.) If the vector is at a degree, change it so that it is represented by a horizontal x and a vertical y.

3.) Solve for x and y.

4.) Add up final x and final y with the Pythagorean therom.

5.) Use some simple trigonometry to solve for the angle.