motion isci 2002. speed: change in distance over time speed = d / t constant vs. average speed...

Motion

ISCI 2002

• Speed: change in distance over time

• Speed = d / t

• Constant vs. Average Speed

• Speed is a ‘scalar’ quantity • No directional properties

Speed Speed

• Velocity: includes the speed of an object plus direction.

• Velocity = d / t + direction!

• Displacement • Object moves from one location to another • Distance and direction from a starting point

Velocity Velocity

Displacement Displacement

• Vectors: have both magnitude and a direction • Velocity, acceleration, displacement, etc.

• Vectors are represented by arrows

Velocity and Displacement are Vectors Velocity and Displacement are Vectors

• Parallel vectors can be summed

• When vectors are at right angles• (a) can be summed • (b) use trigonometry rules to solve

• Pythagorean Theorem

• How is the direction calculated?

Vector SummationVector Summation

Vector AdditionVector Addition

• The so-called parallelogram law gives the rule for vector addition of two or more vectors. For two vectors and , the vector sum is obtained by placing them head to tail and drawing the vector from the free tail to the free head.

Vector Resultant Vector Resultant

• Acceleration: is a change in the velocity of an object.

• Acceleration = v / t

• When you change directions, slow down, speed up, turn you are undergoing acceleration.

• Acceleration may be (+) or (-)

Acceleration Acceleration

• Speed or velocity at any given moment in time • Speedometer in your car

Instantaneous Speed and Velocity Instantaneous Speed and Velocity

When speed is not constant

draw a tangent across the point in time

• Graphs• Straight-line or linear slope indicates a direct or

proportional relationship between the variables • Speed or velocity at that specific time

• If not proportional • Slope of the line tangent to the curve of the line

Motion and GraphsMotion and Graphs

• Slope: rise/run

• Change in position (y) over time (x)

Graphical Slopes Graphical Slopes

Calculating the Slope of a GraphCalculating the Slope of a Graph

Distance-Time Graphs Distance-Time Graphs

Constant velocity (+10 m/s); No acceleration

Changing, positive velocity – acceleration (change in velocity)

Constant Velocity – No AccelerationConstant Velocity – No Acceleration

Velocity – Time Graphs Velocity – Time Graphs

Zero Acceleration

Constant Velocity – Zero AccelerationConstant Velocity – Zero Acceleration

Velocity-Time Graphs (Acceleration) Velocity-Time Graphs (Acceleration)