Question

a) You have taken a video of an ice-skater moving left to right on your phone's screen. You decide to plot the data of position versus time, and send it to a friend who also wants to make a graph.   (You both have the same Physics instructor with the same quirky homework).   While you agree the left to right distance is positive, you make your graph based on the skater's distance from the LEFT edge, while your friend makes her graph as if distance is measured from the RIGHT edge of the camera screen.    How do your graphs differ?

b)  During baseball practice, a batter trying to hit balls to the outfielders accidentally hits a very high popup and then runs the few feet forward it takes and catches the ball when it falls. Which has the greater displacement, the ball or batter?

Answer 1

a) We will plot position on x axis and time on y axis.

Your graph will start from origin as at t=0 the distance of skater from left edge is 0 and your graph will be in upwards right direction as with the increase in time the distance from left edge is also increasing.

However your friend's graph will start from negative x axis as intial position from right edge is in negative direction ( as positive direction is from left to right) and the final position is zero as the ice skater has reached right end. So the curve will start from negative x axis and end on positive y axis ( the graph will rise in right upward direction from the start).

b) Both the ball and the batter will have same displacement as both have same initial and final position ( displacement is distance between final and initial position).