Physics Chapter 3 Notes PDF

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Professor Jun Xiao Lecture Notes Chapter 3...

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Chapter 3 Notes: Linear Motion Motion Is Relative • Motion of objects is always described as relative to something else. • Unless stated otherwise, we mean the motion relative to the surface of Earth. Speed • Speed: the distance covered per unit of travel time. • SI Unit: m/s; • Other Units: km/h, mph. Instantaneous Speed • Instantaneous speed: the speed at a specific instant of time. – Your speedometer shows your instantaneous speed. (e.g. 40 mph, if it continued at that speed for an hour, it would cover 40 miles.) Average Speed • Average speed: – In planning a trip, the driver is concerned with the average speed. The average speed of driving 30 km in 1 hour is the same as the average speed of driving A. 30 km in 1/2 hour. B. 30 km in 2 hours. C. 60 km in 1/2 hour. D. 60 km in 2 hours. Velocity • Velocity is a vector – magnitude and direction, "directed" speed. – “how fast” and “in what direction”. – e.g. a car travels at 60 mph to the north. – Symbol: v. • SI Unit: m/s. • e.g. The speedometer of a car moving to the east reads 100 km/h. The car passes another car that is moving to the west at 100 km/h. Do both cars have the same velocity? Constant Speed and Constant Velocity Constant speed: steady speed, neither speeding up nor slowing down. Constant velocity: constant speed + constant direction (straight-line path). Acceleration Acceleration: the rate of change in velocity over time. change in velocity • In equation form: Acceleration = • Symbol: a. time interval • SI Unit: m/s2. • e.g. If your car's speeding up from 30 mph (13 m/s) to 50 mph (22 m/s) in 10 s, what's its acceleration?

a=

v f  vi t

Acceleration and velocity are actually A. the same. B. rates but for different quantities. C. the same when direction is not a factor. D. the same when an object is freely falling  

Velocity is the rate of change in position over time. Acceleration is the rate of change in velocity over time....