## anonymous one year ago An arrow travelling at 45 m/s strikes and embeds itself in a 450 g apple which is initially at rest. They move off horizont ally at 12 m/s after impact. What is the mass of the arrow?

1. anonymous

i did m(45)+(0)(450)=(450)(12), what am i doing wrong ? @Michele_Laino

2. Michele_Laino

the right equation, is: $\Large m \times 45 + 0 \times 450 = \left( {m + 450} \right) \times 12$

3. anonymous

i havve to find 1 m so why is their two

4. anonymous

?

5. Michele_Laino

since after the impact, te arrow and the apple are ambedded each other, so their momentum is: $\Large \left( {m + 450} \right) \times 12\;\frac{{{\text{grams}} \times {\text{m}}}}{{{\text{sec}}}}$

6. Michele_Laino

after a simple computation, we get: $\Large m = \frac{{450 \times 12}}{{33}} = ...{\text{grams}}$

7. anonymous

what happned to the other "m"?

8. anonymous

when we simplify it ?

9. anonymous

@Michele_Laino

10. Michele_Laino

the mass of apple is 450 grams

11. anonymous

i mean the m on the left side

12. anonymous

when we solve for one variable you can't have 2

13. Michele_Laino

here are more steps: $\Large \begin{gathered} m \times 45 + 0 \times 450 = \left( {m + 450} \right) \times 12 \hfill \\ 45m = 12m + 450 \times 12 \hfill \\ 33m = 450 \times 12 \hfill \\ \end{gathered}$

14. anonymous

ohhh