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.