# Physics 2

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• Motion,Energy,Electricty
• Velocity and Distance-Time Gaphs
• Speed and velocity are both measured in m/s
• speed is just how fast you are going with no direction.         But velocity must have direction specified (30mph north)
• Its how fast you are going
• speed= distance/tim-e
• Acceleration
• is how quickly the velocity is chaning
• something speeds up
• this change in velocity can be changed in speed or a change in direction or both
• formula= change in velocity/time taken
• Example: A cat accelerates from 2 m/s to 6m/s in 5.6 seconds. Find its acceleration? A=  6-2=4/5.6=0.71M/S2
• units of acceleration is m/s2 (little two)
• Distance-time graphs
• Important Notes
• flat sections are where its stationary (stopped)
• straight uphill or downhill section means steady speed
• the steeper the graph the faster its going
• downhill section means its going back towards the starting point
• curves represent acceleration or deceleration
• a steepening curve means its speeding up
• A levelling off curve means its slowing down
• Physics 2
• Acceleration and velocity-time graphs
• Velocity-time graphs
• Important notes
• flat sections represent steady speed
• steeper the graph the greater the acceleration or deceleration
• uphill section are acceleration
• downhill sections are decelerations
• the area under any section of the graph is equal to the distance travelled in the time interval
• a curve means changing acceleration
• Weight,Mass and Gravity
• Gravational force is the force of attraction between all masses
• on the surface of a plant it makes all things accelerate towards the ground (10m/s2)
• it gives everything a weight
• Weight and mass aren't the same thing
• Mass is the just the amount of "stuff" in a object
• weight is caused by gravitational force( pull force)
• an object has the same mass whether its on earth or the moon, but weight will be different (less gravitational force on moon)
• Weight is a force measured in newtons. Mass is not a force-its measured in KG.
• Weight=mass X gravitational field strengh
• Example: what is the weight in newtons of a 5g mass, both on earth and moon?          A"W=MXG" E=5x10=50N M=5X1.6=8N
• Gravity on earth=10n/kg Gravity on moon=1.6n/kg