Question

( Chapter 2 Part 2 9 of 11 Problem 2.47 Constants 1 Periodic Table Mary and Sally are in a Soot race (see figure (Figure )) When Mary i 22 from the finish line, she has a speed of 4 0 m/s and is 5 0 m behind Sally, who has a speed of 5 0 m/s Saly thinks she has an easy win and se during the remaning poršion f 0 42 m/ to the finish line What censtant acceleration does Mary now need duing the remaining porion of the race, if she wbhes to cross the fnish line side-by side with Saly? Express your answer using two significant figures of the race, decelerates at a constant rate Figure 1 of 1 Finish Provide Feedback Mary Sally 22 m Type here to search 5 6 7 8

Answer 1

Given is:-

speed of Mary

speed of Sally

decleration of Sally

Now,

Let the time taken by Sally to reach the finish line is = t seconds, then using the second equation of motion we get

by plugging all the values we get

solving for time t we get

Now,

If marry want to finish the race side by side then she has to cover the 22m distance in this time

therefore again using second equation of motion we get

by plugging all the values we get

which gives us

Thus the required acceleration of Mary is 0.66 m/s²