Motion,%20Speed,%20Velocity,%20and%20Acceleration

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Motion, Speed, Velocity, and Acceleration

• Nadia Reese
• 6th grade science

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Motion

• Motion- when an object changes its position
  relative to a reference point.
• In order to know something has moved, you need to
  know the point from where it started.

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Distance

• Distance how far an object has moved.
• The SI unit of length is the meter (m).
• Longer distances are measured in kilometers (km).
• Shorter distances are measured in centimeters
  (cm).

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Time

• Time - an instance or single occasion for some
  event.
• The SI unit of time is the second (s).
• Other units for time are the minute, hour, days,
  years, etc

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Speed

• Speed the distance an object travels divided by
  how long it took (time).

37.5 km/hr
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Instantaneous Speed

• The speed at a particular point in time.
• Example-speedometer in car.

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Constant Speed

• Means that the speed of the object under
  consideration on NOT changing.
• Example-cruise control

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Average Speed

• TOTAL distance traveled divided by the total time
  it took.
• EXAMPLE Trip from El Paso to Las Cruces.

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Velocity

• Velocity the distance an object travels divided
  by how long it took (time) in a certain direction.

37.5 Km/hr West
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Velocity

• The velocity of an object can change even if the
  speed remains constant.
• Ex. going around a curve in cruise control

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Calculating Speed/Velocity

• Vd/t (distance divided by time)
• V Velocity (m/s)
• d distance (m)
• t time (s)

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Example 1

• A bicycle rider travels 60.0 km in 3.5 hours.
  What is the cyclists average speed?

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Example 2

• What is the average speed of the car that
  traveled a total of 300.0 miles in 5.5 hours?

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Graphing Motion

• A distance-time graph makes it possible to
  display the motion of an object over a period of
  time.
• The slope of the line represents the speed. The
  steeper the slope, the faster the speed.
• The horizontal line means that the velocity is
  zero.
• Distance is always plotted on the y- axis and
  time is always on the x-axis.

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Distance-Time Graph
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Distance-Time Graph
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Distance-Time Graph
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Distance-Time Graph
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Distance-Time Graph
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Distance-Time Graph Questions

• What is the speed at B-C? ____________
• How far did the car drive before it stopped the
  first time? _________
• How far did the car drive the whole trip?
  ___________
• How long did the whole trip take? __________
• What is the cars average speed? ___________

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Velocity-Time Graph
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Acceleration

• Acceleration is the rate of change in velocity.
  When the velocity of an object changes, the
  object accelerates.
• Acceleration occurs when an object changes its
  speed, direction, or both.
• When an object increases it velocity it is called
  acceleration, when an object decreases its
  velocity it is called deceleration.

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Acceleration Formula

• a Vf Vi
• -------------
• t
• Vf final velocity (m/s)
• Vi initial velocity (m/s)
• a acceleration (m/s2)
• t time (s)

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Example 1

• A skateboarder is moving in a straight line at a
  speed of 3m/s and comes to a stop in 2s. What is
  the skateboarders acceleration?

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Example 2

• A flying doughnut increases its speed from 30m/s
  to 145 m/s in 11.6 s. What is its acceleration?