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physics/Work Energy and Power/Power.md

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+[[Work Energy and Power]]
+
+Power is how fast energy moves or changes form.
+
+# Summary
+* SI Unit is Watts (W), where 1 W = 1J/s
+* Average power is energy change over time: $P_{avg}=\frac{\Delta E}{\Delta t}$. Work changes energy so $P_{avg}=\frac{W}{\Delta t}$
+* Instantaneous power for a constant force: $P_{inst}=F_{||}v=Fv\cos \theta$ using only force component parallel to velocity.
+* Sign of power tells direction, positive means energy added negative means energy removed.
+* When an object moves at a constant speed, energy is zero.
+
+# Average Power Calculation
+$$P_{avg}=\frac{\Delta E}{\Delta t}$$
+Examples:
+* 60 watt light bulb transfers 60 joules into light and heat.
+* 1500 watt hair drier running for 5 minutes transfers 1500 * 300 watts.
+* Solar panel generating 500 watts per second stores 500 joules to be used later.
+
+# Power as Work Rate
+$$P_{avg}=\frac{W}{\Delta t}$$
+Power can be calculated by dividing work by time taken.
+
+# Instantaneous Force from Power
+$$P_{inst}=F_{||}v=Fv\cos \theta$$