PHY 101 Lecture 3: PHY 101 Chapter 3
Document Summary
Motion is relative: everything in the universe is moving, when we talk about the speed of something, we are talking about it relative to the surface of the earth. Speed: speed = distance / time, a cyclist who covers 16 meters in 2 seconds has a speed of 8 meters per second, common units. The speed at any instant in time. A speedometer in a car shows the instantaneous speed of the car: average speed. Average speed = total distance covered / total time interval. We travel 80 km in 1 hour our average speed is 80km/hr. If we go 320km in 4 hours, the average speed is still 80km/h. Total distance covered: total distance covered = average speed x time interval. Something with a constant velocity is something that is not speeding up or slowing down, and it also does not change direction: changing velocity. This acceleration is caused by the force of gravity.