Double Checking Answer for Finding Final Velocity

[Chu]

A chameleon can accelerate its tongue in order to catch an insect at an impressive rate of 500m/s^2. How quickly must a fly located at 5cm from the chameleon react if it is to escape?

Given:

Vi = 0

V_f = ?

x_i = 0

x_f = 5 cm

a = 500m/s^2

Using the equation:

V_f²=V_i²+2a(x_f-x_i)

V_f=70.71m/s

 

Could someone please double check this answer for me.

 

Thanks!

Edited October 12, 2017 by Chu

[J.C.MacSwell]

does it seem reasonable?

If that is the final velocity the average would be half that...around 35m/s...and it would have taken about a seventh of a second to get to 70.71m/s

You might want to double check the decimal place of your result...

 

[Chu]

I see what I did wrong. I didn't do parenthesis first and went to multiplication.

[J.C.MacSwell]

4 minutes ago, Chu said:

I see what I did wrong. I didn't do parenthesis first and went to multiplication.

Not sure what you mean exactly. What was your result?

[swansont]

You also haven't answered the question.

[J.C.MacSwell]

Really only enough information to answer "time required to react before getting eaten"

[Chu]

I was using the wrong equation! 

using 

X_f=1/2at² 

0.05=1/2(500)*t²

0.05=250*t²

t²=0.0002      square this to get:

t=0.014 s