EOSC 114 Lecture #2.docx

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Published on 16 Apr 2013
School
UBC
Department
Earth and Ocean Sciences
Course
EOSC 114
Professor
EOSC 114-202
January 4, 2013 Learning Goals
Define force
Explain how force of gravity affects motion and energy
List 5 types of energy important to disasters and describe what causes them to vary
Explain how disasters are associated with concentration of energy
Explain how energy conservation applies to natural disasters
Explain why disaster scales are based on the order-of-Magnitude concept and
interpret graphs with logarithmic scales
Disasters and Energy
Energy causes things to move or change
Disasters release immense energy, which cause catastrophic changes
These changes are related to force, work, power, pressure, stress and others
Forces
A force (F) pushes or pulls
The SI unit is the Newton (N), which is equal to 
How big is a Newton?
o 15km/h breeze pushes with 1N force
o the weight of Mt. Baker on the Earth’s crust is about   N
Gravity
A force that attracts matter (ie masses) to each other
Objects of mass m near the Earth’s surface are pulled with force   , where
 
Energy
There are many forms of energy, including:
o (Work)
o Potential Energy
o Kinetic Energy
o Sensible Heat
o Latent Heat
Work (W)
Work W is the force F that pushes an object times the distance d the object moves
(  )
The SI unit of work (and all other forms of energy) is the Joule (J)
o    
If you push hard against a wall that does not move, then you’ve still done zero work
Potential Energy
The work needed to raise an object of the mass m a vertical distance z against the
pull of gravity g is called potential energy PE (    )
Example: Which gains the most PE: Lifting a 2kg object vertically, or rolling the same
object up a frictionless slope to the same height?
o A: They both have the same PE, since the mass is constant (2kg), the vertical
distance is constant (same height) and gravity is constant (9.81m/s2 on
Earth)
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Document Summary

Explain how force of gravity affects motion and energy. List 5 types of energy important to disasters and describe what causes them to vary. Explain how disasters are associated with concentration of energy. Explain how energy conservation applies to natural disasters. Explain why disaster scales are based on the order-of-magnitude concept and interpret graphs with logarithmic scales. Energy causes things to move or change. Disasters release immense energy, which cause catastrophic changes. These changes are related to force, work, power, pressure, stress and others. The si unit is the newton (n), which is equal to. How big is a newton: 15km/h breeze pushes with 1n force, the weight of mt. Baker on the earth"s crust is about n. A force that attracts matter (ie masses) to each other. Objects of mass m near the earth"s surface are pulled with force , where. There are many forms of energy, including: (work, potential energy, kinetic energy, sensible heat, latent heat.

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