What is Motion

Chapter 9

Key Skills

Design and conduct an experiment to test a hypothesis about falling objects

Describe motion using accepted IB Physics notation Measure, describe, and graph the motion of an

object without using complicated equipment Use more scientific techniques and equipment for

investigating motion Interpret and draw graphs of simple motions

Key Terms Variable pitch propeller Conventions Scalar Vector Distance Position Displacement Time Time interval Photogate timer Rate of change

Speed Velocity Acceleration Instantaneous Linear motion Precision Readability Vector sum & diagram Ticker tape timer Ultrasonic motion detector Position time graph

Canadian Transport Technologies

Canadian Transport Technologies (Bombardier)

Transportation in Canada

Two obstacles to transporting good and people:

1. Harsh Climate

2. Population thinly spread out over vast distances

Transportation in Canada

Canadian inventors, scientists, and engineers have come up with some ingenious solutions to meet the challenges of moving goods and people in Canada.

Keep at the back of your mind: What theoretical knowledge would help in analyzing

the problem? What technical skills would be needed to build

devices to solve the problem? What other problems came up as a result of trying to

solve the initial problem and what other opportunities might arise from these?

Transportation in Canada

When riding your bike, you have to pedal hard to get up to cruising speed. Once you reach cruising speed to don’t have to expend so much energy pedalling.

Similarly, a car without a transmission would have its engine running slow at low speed and really fast at high speeds. This would waste gas and cause wear and tear on the engine.

Transportation in Canada

Early aircraft had similar problems where the engine was directly connected to the propeller. To control the power output, the pilot could only change the engine speed. This meant that high speeds were needed for takeoff and had to be maintained in flight when they were not needed. There was no transmission for the engine- they would be too heavy.

Transportation in Canada The solution to this problem

was developed in 1916 by New Brunswick inventor Wallace Turnbull (1870-1954). It was called the variable pitch propeller. The pitch is the angle at which the blades are set into the hub. By varying the angle engine power output could be adapted to needs for takeoff, cruising & landing. It is one of the most important inventions in aviation history

Transportation in Canada

Elsie MacGill (1905-1980) was the first woman electrical engineer in Canada. She turned a railway box car factory in Thunder Bay, ON into an aircraft manufacturing plant producing the Hawker Hurricane Fighter plane. These planes played a major role in the Battle of Britain against Germany(1940-41).

She also designed skis and de-icing equipment for cold weather flying and developed the Curtis Helldiver plane for the US Navy as well as the Maple Leaf trainer

Transportation in Canada

Transportation in CanadaOther Canadian contributions

AVRO Jetliner AVRO Arrow jet fighter Bush planes e.g. Norseman, Beaver, Otter,

Twin Otter G-suit (prevent pilot s from losing

consciousness during high speed manoeuvres)

STEM Antenna (space vehicles) Canada Space Arm (Robotic)

Winter Transportation: Defeating the Snow

During late 19th century railways were extended rapidly across North America. In Canada, we had the Canadian Pacific Railway (CPR) and the Canadian National Railway (CNR)

Railways were the fastest and cheapest way of transporting people and freight over long distances.

However, they were often paralyzed by severe winter weather conditions. Even today’s locomotives can be sidelined by winter storms

Winter Transportation

In 1869, J.W. Elliott, a Toronto dentist patented a compound revolving snow shovel to fit the front of locomotives. The shovel had two paddle wheels which threw the snow to either side. Railway officials were uninterested.

In 1883, Orange Jull improved on Elliott’s design by adding a cutting wheel in the center and reducing the revolving paddles to one. It was a success!

After 1909, George Bury, a railway official, designed a huge, reinforced plow which could cut through 19 cm thick tree trunks. It also was successful.

Winter Transportation

Today’s snowblowers work on the same principle.

Canadian companies such as Bombardier in Montreal still lead the way in developing railroad technologies.

The Language of Motion

A scalar is a physical quantity that has magnitude only e.g. time 4.0 s. Note only one number is needed to specify a scalar.

A vector is a physical quantity that has both magnitude and direction e.g. displacement 5.2 km East

Examples of scalars & vectors

Scalars Vectors

Distance Displacement

Speed Velocity

Time Acceleration

Density Force

Definitions

Conventions are agreements about the way something is done e.g. right is + and left is –

Readability refers to the smallest division on the scale e.g. a metrestick is readable to the nearest millimetre (mm).

Linear Motion refers to motion in a straight line.

Definitions

Distance refers to the total length of a path taken or how far an object is from a reference point (origin). It is a scalar quantity.

Time describes when en event occurs e.g. class starts at 9:00 am

Time Interval describes the duration of an event e.g. Science class lasts for 75 minutes.

Δt = tf - ti

Definitions

Position describes the location of an object as seen by an observer usually in relation to a reference point ( often taken as the origin). It is a vector quantity e.g. the accident took place 10. km west of the city

Displacement is a vector quantity and refers to the change in position of an object e.g. we walked 4 blocks north of the fire station.

Δd = df – di

Note the IB symbol for displacement is s

Definitions

Speed refers to the distance travelled in a specific time interval e.g The Jones family averaged 85 kmh-

1 on the way to their cottage. (symbol v) Velocity refers to the rate of change of position of

an object e.g I travelled 100 kmh-1 West on Hwy 101.(IB symbols u = initial velocity; v = final velocity)

Acceleration refers to the rate of change of velocity. It is a vector quantity whose units are ms-2

e.g. the acceleration due to gravity is 9.81 ms-2

down.(symbol a)

Definitions

Position-time graph is a graphical representation of the relationship between position and time with time on the horizontal axis.

Ticker Timers are devices which record the motion of an object as a series of dots made on paper tape by a vibrating arm of an electric motor.

Definitions

Ultrasonic Motion Sensors use high frequency sound waves emitted in pulses which bounce of an object and are detected by the device. The data can be output to a computer or screen as a graph.

Photogate timers are devices with light-sensitive photocells which can measure short time intervals and allow calculation of velocity or acceleration.

Definitions

Change refers to the increase or decrease of a physical quantity e.g. Δd = df – di

Rate of change refers to how fast a quantity is changing e.g. v = Δd/Δt or a = (v-u)/t

E.g. the shoreline is eroding at the rate of 10 cm per year