Motion Distance, Displacement Speed, Velocity, and Acceleration

Motion

Distance, Displacement Speed,

Velocity, and Acceleration

Tools to Describe Motion

Language (Text) Diagrams and Maps (Figures) Measurements (Variables) Tables, Graphs and Charts

(Organizers) Equations (Mathematics)

Distance (d) & Displacement (∆x) Is a measure of the

length of the path of a moving object.

Is a scalar, since it has no direction.

Units: Meters

Is a change in position of the object and is a measure of the direct distance from start to finish .

Is a vector, since it has direction.

if xxx

Motion Motion is a change in position

relative to a frame of reference Speed is the distance traveled

in a given amount of time

Time

ceDisSpeed

tan

t

xx

t

dv if

Types of Speed Constant Speed: Is

when speed stays the same. The ratio of d/t is always constant.

Changing Speed: Is when speed changes, the ratio d/t is not a constant

Instantaneous Speed: Is the speed at that moment. Ex. Speedometer reading.

Average Speed: Is total distance / time

Units for Speed

The units for speed: meters/second (m/sec) kilometers/hour (km/hr) Miles per hour (mph) is a

non metric unit of speed.

Average speed

Total distance divided by the total time

Formula:

t

x

TotalTime

ceTotalDisedAverageSpe

tan

Velocity Speed in a given direction Velocities in the same direction

combine by adding Velocities in different

directions combine by subtracting

Interesting facts

Rockets are launched in the same direction of the earth’s rotation to get an extra boost of 1800 km/hr to its speed

Likewise airplanes takeoff in the direction of the wind and land against the wind.

Questions (Bell ringer)

What is a frame of reference?

Why do we call it so? What is the most common

frame of reference? What is the frame of

reference for the sunset?

Frames of Reference (Answers) It is the object or point from which

movement is determined. Since movement is relative to an

object that appears to be stationary.

Earth is the most common frame of reference.

The earth.

Questions (Bellringer) What is motion? What is speed? How is it calculated?

What is average speed?

Questions (Bellringer)

How is velocity different from speed?

Which two factors determine an object’s velocity?

Acceleration The change in velocity Acceleration is measured in

m/sec/sec or m/sec2

Formula is: (final velocity - original

velocity)/time

t

vva if

Deceleration vs. Acceleration A decrease in velocity is

deceleration NOT negative acceleration, which is acceleration in the negative direction.

A distance-time graph for acceleration is always a curve

Centripetal Acceleration

Acceleration directed toward the center of circular path

Questions What is acceleration? What is the shape of a

distance-time graph for acceleration?

What is centripetal acceleration?

Momentum Momentum is equal to the mass of an object times its velocity

momentum= mass x velocity

Conserving Momentum The law of conservation of momentum states that the total momentum is NOT lost, only transferred

Questions What is momentum? What happens to momentum

as the mass of a moving object increases?

What is the formula for momentum?

What is the law of conservation of momentum?