Physics 1010Q
Lecture # 2
Chapter 2
What is Motion?
Earth moves round the sun
A player kicks a ball
A swimmer swims across the swimming pool.
1.
Speed
Imagine driving home from school.
For simplicity, assume that you can drive home in a straight line.
One relationship between space and time can be illustrated by answering the question,
“
How fast were you going?
”
Actually, there are two ways to answer this question:
looking at the total trip, and
considering the momentbymoment details of the trip.
Average speed
is defined as the total distance traveled divided by the time it took to cover this
distance.
±
²
³
where
S
is the average speed,
d
is the distance traveled, and
t
is the time taken for the trip. We
measure speed as m/sec.
Q:
Someone rides a bicycle in a straight line and
covers a distance of 100 meter (from north
end of the Student Union to the Coop) in 50 seconds. What is the average speed?
A:
Q:
A student rides a bicycle in a straight line at a speed of 10m/sec for 10 seconds, then stops
to rest for 10 seconds, then rides in the same direction for 10 seconds more at a speed of
10 m/sec. What is the average speed over the entire 30 seconds interval?
Ans:
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Problem:
Suppose you live 40 km from school and it takes you 2 hours to drive home.
What is your average speed during the trip as m/sec
A:
Problem:
What is the average speed of an airplane that flies 3000 km in 6 hours?
A:
Problem:
Someone rides a bicycle in a straight line at a speed of 10 m/sec for 10 seconds, then
stops to rest for 10 seconds, then rides in the same direction for 10 seconds at a speed of 10
m/sec. What is the average speed over the entire 30 seconds interval?
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 Spring '11
 fsomething
 Physics, Acceleration, Velocity, Galileo

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