Transcript What is this lesson about?

Objectives
By the end of this topic you should:
Levers
Big question
• How many weights can I place on the ruler
before it tips?
Hydraulics
Pressure = Force
Area
• Weight measured in
Newton's N
• Area measured in
meters squared M2
• Pressure measured
Newton meters
squared
N/ M2 or NM - 2
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If you push down one side 5 M
the other will move?
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Centre of gravity
Center of gravity can be out side
the object
• http://www.youtube.com/watch?v=QQh56
geU0X8
Pendulum key words
• Amplitude (how far from vertical the string
moves)
• Period ( time taken for one swing)
• Frequency ( number of swings per secon)
Which falls faster heavy or
light?
• http://www.bing.com/videos/search?q=hap
per+feather&view=detail&mid=4B4A1DFA
822F65022B7B4B4A1DFA822F65022B7B
&first=0&FORM=NVPFVR
Cirular motion
• http://www.bing.com/videos/search?q=wall
+of+death+fair+ground&view=detail&mid=
0A8553C1DD64230FA31E0A8553C1DD6
4230FA31E&first=0&FORM=NVPFVR
Centripetal force
• Is any force that acts at 90 degrees to
objects motion (towards centre of circle) of
object.
• With out which object flies off in straight
line
• http://spacewar.oversigma.com/
Magnetic feilds
The earth acts as a magnet
The earth acts as a magnet
• Arrows on field are drawn
north to south
• Where the lines are close
together the field is strongest
• In electromagnets field can
change direction by
changing the current
• http://www.bing.com/videos/search?q=fara
day+electric+motor&view=detail&mid=2F7
A37DE404A15A0777A2F7A37DE404A15
A0777A&first=0&FORM=NVPFVR
Make a stronger motor
• More coils of wire
• More current
• Stronger magnet
• (changing direction of current changes
direction of spin)
• http://www.bing.com/videos/search?q=ele
ctric+motor&view=detail&mid=C357EF84B
0840FC41766C357EF84B0840FC41766&
first=0&FORM=NVPFVR
Practical problems
Step up transformer
• Always
with
respect
to
voltage
Less coils
more coils
Step down transformer
• Always
with
respect
to
voltage
Less coils
more coils
Stepping up
• 12
22
Stepping up
• 1:2 ratio voltage times 2
•
•
•
•
1:2 ratio voltage times 2
1:3 ratio voltage times 3
1:4 ratio voltage times 4
1:5ratio voltage times 5
• Ratio = big number / small one