Black Hands

649 Words3 Pages
I.

Motion

Motion
• An object is in motion when it is undergoing a continuous change in position. – Position
• Location of an object
– Reference point
– Measurement scale

• Ex. table is about 3m from the door

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3-2

Motion
• Is described by using the fundamental units of length and time
• Combining the length and time will give you the time rate of change of position
– Basis of describing motion in terms of speed & velocity

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3-3

Speed & Velocity
• In Physical Science ‘speed’ and
‘velocity’ have different (distinct) meanings. • Speed – a scalar quantity, only magnitude – A car going 80 km/h

• Velocity – vector, both
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Section 2.2

2-9

Example #1
• The driver of a car moving at 72 km/h drops a road map on the floor. It takes him 3.00s to locate and pick up the map. How far did he travel during this time? Copyright © Houghton Mifflin Company. All rights reserved.

3-10

Acceleration
• Changes in velocity occur in three ways:
– Increase in magnitude (speed up)
– Decrease in magnitude (slow down)
– Change direction of velocity vector (turn)

• When any of these changes occur, the object is accelerating.
• Faster the change  Greater the acceleration • Acceleration – the time rate of change of velocity
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Section 2.3

2-11

Acceleration
• A measure of the change in velocity during a given time period change in velocity
• Avg. acceleration = time for change to occur Dv vf – vo
(vf = final & vo = original)
• a=
=
t t • Units of acceleration = (m/s)/s = m/s2
• In this course we will limit ourselves to situations with constant acceleration.
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Section 2.3

2-12

Example #2
• A bicycle moves from rest to 5m/s in 5s.
What was the acceleration?

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3-13

Example #3
• A race car starting from rest accelerates uniformly along a straight track, reaching a speed of 90km/h in 7.0s.
What is its acceleration?

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