Evans SPH 3U1

Unit 1: Kinematics

Note 1: Intro to Kinematics

Reference: Chapters 1.1, 1.2

Definitions:

Mechanics - study of the motions of objects and the forces that act on them

Kinematics - study of the motion of objects

Dynamics - study of the forces acting on moving objects

Statics - study of forces acting on objects at rest

Let's look at Kinematics:

Uniform Motion - movement in a straight line at constant speed.

Non-Uniform Motion - movement involving changes in speed and/or direction

Scalar Quantity - a physical quantity described by a number and a unit. (i.e. speed, time, work, length)

Vector Quantity - a physical quantity described by a number, a unit and a direction. Proper vector notation has an arrow above the symbol ( ).  Examples are displacement, velocity, force, acceleration.

Distance - the length of the path an object travels

Position - the distance and direction of an object from a reference point ( ).

Displacement - the change in the position of an object ()

Example 1: A students runs five 10 metre laps. What is the distance she travelled? What is the displacement?

Example 2: A student trvels 100. m [E}, 50. m [S] and then 50. m[N]. What is a) the distance travelled?

b) the displacement?

Speed - the distance travelled divided by the time (scalar)

Velocity - the rate of change of position (vector)

Average Speed - total distance traveled divided by the total time taken.

Average Velocity - the displacement (i.e. change of position) divided by the time interval.

See Example 1 page 8

Do following examples in group circular solving:

Example 3: What distance will a plane travel during 30 seconds if the speed it is traveling at is 360 km/h?

Example 4: A rabbit rungs 92m[E] in 12 seconds, 143m[N] in 18 s, 55m[S] in 9.0 s, rests for 10s, runs 27m[W] in 5.0 s. What is the average speed of the rabbit?

Example 5: A duck travels with uniform motion from a position of 2.0 km[N], to a position of 7.0 km [N], to a position of 20 km south in 0.50 h. Find the duck's

a) distance

b) speed

c) displacement

d) velocity

Example 6: The turtle and the hare have a race around a track. The distance around the track from the start/finish line is 200m. The hare finishes in 40 s and the turtle in 7.8 hours. What is the average velocity of each animal?

Assign directions properly / Understand negatives in kinematics (Chpt 1.3, 2.2)

Analyze negative Velocity.

Pg 13  #2,3,4,5bd,6