Blog 13: CANNONS

Today, Mr. Chung introduced us to a new assignment: CANNONS!

Our main goal is to create a cannon that would shoot the cannonball as far as possible.
In physics terms, we need to build a cannon that would produce the greatest range in the x-axis.

The main factor that determines how far it will go is the angle. A longer barrel would be better because the energy would be applied for a longer period of time; however, it wouldn't work like this for our cannons because our cannonballs are not starting from all the way inside it.

We are only allowed to use 5 pop cans and duct tape. The cannonball is to be made of 2 styrofoam cups tape together to form a closed "cylinder".

Blog 12: Dynamics

In the dynamics unit, there are four major topics: Equilibrium, inclines, pulleys and trains.

Equilibrium 

      In an equilibrium, the forces cancel each other out to make everything equal. In simpler terms, nothing moves when there is equilibrium.

Equlibrium problem

Inclines

     There are two kind of incline problems: Kinetic and static. In an incline, there is friction as the object slides down or as it begins to slide down.               

                                         

Incline problem



Pulleys

Assumptions:

• set your positives (+ in direction of acceleration)
• no air resistance
• T₁ = T₂
• 2 systems - 2 FBDs
• acceleration of both systems are same  

Pulleys problem part 1



Pulleys problem part 2

Trains

Assumptions:

• no air resistance
• set your positives (+ in direction of acceleration)
• no acceleration in y direction
• cords (between the cars) are weightless
• # of FBDs is equal to number of masses



Train problem part 1



Train problem part 2



You should always write the assumptions, as soon as you draw your FBDs



Blog 11: PROJECTILE MOTION

What is projectile motion or parabolic motion?

Any body that is given initial velocity and then follows a path determined by the effect of the gravitational acceleration and by air resistance (air resistance is usually neglected in physics because we want to make it easier to calculate everything)

This image shows an example of a parabolic motion/projectile motion

Gravity (g or sometimes a_g) is always set to 9.81m/s² on Earth

Without the effects of gravity and air resistance, an object would be able to move forever without stopping unless it bumps into something.

Big 5 Equations

          Although the big 5 equations were first used for linear problems, we started to use these for projectile motion. Acceleration is always assumed as 9.81m/s² unless another acceleration is given. 

          The velocities are split into x-components and y-components. In parabolic motion, the x-component is the same throughout, i.e if it started with a velocity of 2m/s it will end with a final velocity of 2m/s. However, this is not the case for the y-component as the gravity gives the object acceleration. This acceleration means that the velocity will be either increasing or decreasing depending on the direction that the object is traveling in. Going up would slow it down and vice versa. Therefore, when the object is going down, the y-component will increase as will the displacement.

      

Blog 10: ROLLERCOASTERS~

Today, we were given our ISUs (Independent Study Units). One of the assignments was to build a rollercoaster, that would be entered into the annual competition at Paramount Canada's Wonderland. This assignment will be a long, difficult one and it will be due on January.

Here is my favourite coaster:

This rollercoaster won for the Artistic Category in 2009

Blog 9: Adding or Subtracting Vectors

There are two main ways to go about adding or subtracting vectors:

1. Use a scale diagram

a) Measure and draw vectors in scale (1cm=1km)
b) Connect the head to tail
c) Resultant is always origin to destination (AYJackson to PMall :P)
d) When you "subtract" vectors, you are actually adding in the opposite direction (12km[N] can be rewritten as -12km[S])

e) Use a protractor to measure the angle in accordance to North and South.

2. Add or subtract by components

a) Set you positive axes

b) Break all vectors into two components (x and y)

c) Solve for ∑x and ∑y (summation of x and y)

d) Use Pythagorean Theorem to add the two sums of components (∑x and ∑y)

e) Use trigonometry to solve for angle

        SOH → sinθ = opp/hyp

        CAH → cosθ = adj/hyp

        TOA → tanθ = sinθ/cosθ = opp/adj

Blog 8: Position-Time & Velocity-Time Graphs

Position vs Time Graphs

Stayed for 1 second at a distance of 1m

Walked away for 2.5 m in 2 seconds 

Stayed at 2.5 m for 3 seconds

Walked approximately 1 m towards in 1.5 seconds 

Stayed for 2.5 seconds at 1.5 m

Walked towards 1.5 m from 3 m for 3 seconds

Stayed for 1 second

Walked towards 1 m for 1 second

Stayed for 2 seconds 

Walked away 2.5 m for 3 seconds

Walked away 1 m for 3.5 seconds

Stayed for 3 seconds

Walked away 1.4 m for 3.5 seconds

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Velocity vs Time Graphs

Stayed for 2 seconds 

Walked towards at 0.5m/s for 3 seconds

Stayed for 2 seconds 

Walked backwards at 0.5m/s for 3 seconds

Speed up from 0 m/s to 0.5m/s for 4 seconds 

Walked at 0.5m/s for 2 seconds

Walked backwards at 0.4m/s for 3 seconds

Stayed for 1 second

Walked at 0.36 m/s for 3 seconds 

Walked backwards at 0.4m/s for approximately 3.75 seconds 

Stayed for approximately 3 seconds

Blog 7: Building an Electric Motor

               On Wednesday, Mr. Chung gave an interesting assignment to the class: We were to create our own electric motors. He asked us to bring our own materials if we could.

Materials:

·         paper clips

·         cork

·         pop can

·         sandpaper

·         thumbtacks

·         stick (axel)

·         nails

·         pins (commutator)

·         scissors

Mr. Chung provided us with most of the materials, including a hammer. He gave us short instructions and hints throughout the lab, such as how the coils should be in parallel to the nails, not perpendicular. If you were to coil them perpendicular

This lab was very effective, for me anyway, because it was a hands-on activity. I got much more out of it then I would have from listening to how it works.

Eddie and I completed our electric motor and presented it to Mr. Chung. He hooked the two pop can sheets (brushes) with 2 wires, which were connected to a large battery. He switched the power source on and our cork started turning very quickly, only slowing down once every few seconds.

On Friday, we took our motor for another spin so we could film it, but it didn’t work as well as the day before. It still worked though…

Here is our video of the motor: