Question

could someone tell me if these answers are correct? I missed my teachers lesson<<

9. D
10. a) .037 m/s
b) not enough info

**Postin pic

Answer 1

or is a and b the same answer? since speed is basically velocity...

Answer 2

Hi! I agree with your answer for 9!

Answer 3

cool and 10? << lol I think i may have messed up

Answer 4

For that one, we look at \(\bar v=\dfrac{\Delta x}{\Delta t}\) for velocity. And you are right, we can't know what the average speed is!

Answer 5

cool so both answers r correct then..?

Answer 6

wait i think i did something wrong! i divided by the wrong number i think lol

Answer 7

is it .012 m/s?

Answer 8

I got a different answer for 10a!

\(\bar v=\dfrac{x_2-x_1}{t_2-t_1}=\dfrac{8.5\ [m]-2.7\ [m]}{6.0\ [s]-(-3.0\ [s])}\\~\\\qquad\qquad=\dfrac{8.5\ [m]-2.7\ [m]}{6.0\ [s]+3.0\ [s]}=\dfrac{5.8\ [m]}{9\ [s]}=.6\bar4\ [m/s]\\~\\\qquad\qquad\approx.64\ [m/s]\)

Answer 9

ohhh i see what you did there! i added instead but i understand now. Thank u so much!! But may i ask, what info and equation would i use if to find the average speed then?

Answer 10

cuz i think i may have used the average speed formula to get my answer but it's wrong lol

Answer 11

Oh! Haha, with average speed, you don't want the change in position (\(\Delta x\)), but the change in the distance traveled. The distance traveled will be positive with increasing time, because it is not a vector and so direction is not considered (so no negative signs!).

To find average speed, you need the change in distance, rather than displacement (change in position).

Answer 12

Which formula did you use? If I recognize it, I'll let you know what it is!