Presentation on theme: "Monday, August 25, 2014 Day 2 Science Starters Sheet 1. Please have these Items on your desk. 2- Science Starter: Which of the scientists you saw in the."— Presentation transcript:
Monday, August 25, 2014 Day 2 Science Starters Sheet 1. Please have these Items on your desk. 2- Science Starter: Which of the scientists you saw in the movie Friday, do you think contributed the most to Einstein's theories and why? Agenda
Update table of contents PageDateActivity 23 8/25Motion Part 1 notes (Distance and Displacement)
Motion – Part 1 Frame of Reference Distance vs. Displacement
Look at the figures. In fig.1, the car is to the right of the tree. In fig.2, after 2 seconds, the car is to the left of the tree. As the tree does not move, the car must have moved from one place to another. Therefore, here the tree is considered as the frame of reference.
Distance vs. Displacement Distance- total path length, no particular direction Displacement- The length of the straight line drawn from the initial position to the final position of an object. – The change in position of an object – Has a specific direction
How far have I gone?
Distance or displacement? There are two ways to answer this question. On the one hand, there's the sum of the smaller motions that I made: two meters east, two meters south, two meters west; resulting in a total walk of six meters. On the other hand, the end point of my walk is two meters to the south of my starting point. So which answer is correct? Well, both. The question is ambiguous and depends on whether the questioner meant to ask for the distance or displacement.
Distance vs. Displacement Let's clarify by defining each of these words more precisely. Distance is a scalar measure of the interval between two locations measured along the actual path connecting them. Displacement is a vector measure of the interval between two locations measured along the shortest path connecting them.
How far does the earth travel in one year? In terms of distance, quite far (the circumference of the earth's orbit is nearly one trillion meters) In terms of displacement, not far at all (zero, actually). At the end of a year's time the earth is right back where it started from. It hasn't gone anywhere.
Distance vs. Displacement You drive the path, and your odometer goes up by 8 miles (your distance). Your displacement is the shorter directed distance from start to stop (yellow arrow). What if you drove in a circle? start stop
Distance Vs. Displacement cont. Distance and displacement are not necessarily equal to one another. Calculating displacement – Assign + and – designations for the direction + to the right, N, or E - to the left, S, or W – Displacement ∆x= change in position Final position- initial position ∆x= X f -X i
Displacement practice Start= 5m End= 10 m X i = -1 m X f = 5m X i = 5m X f = -1m