# Chameleons catch insects with their tongues, which they can rapidly extend to great lengths. In a typical strike, the chameleon's tongue accelerates at a remarkable 240 m/s for 20 ms, then travels at constant velocity for another 30 ms.`<br> ` During this total time of 50 ms, 1/20 of a second, how far does the tongue reach?

## Expert Answers Initial velocity: `v_0 = 0 ` `m/s `

Acceleration: `a=240 ` `m/s^2 ` , for `20 ` `ms `

Equations:

`Delta s = 1/2 a *t^2` ,

`v=a* t ` ,

`Delta s=v_(const)* t `

Distance tongue travels do to acceleration:

`Delta s_(a) = 1/2 (240 m/s^2)(20*10^-3 s)^2`

`=6/125=>0.048 m=4.8 cm `

Constant speed after `20 ms ` :

`v_(const) = (240 m/s^2)(20*10^-3 s)=12/5=>2.4 m/s `

Distance tongue travels do to constant speed:

`Delta s_(const) = v_(const) * (30*10^-3 s) = 0.072 m = 7.2 cm `

Total distance tongue reaches:

`Delta s_ = Delta s_(a) + Delta s_(const) = 4.8 cm + 7.2 cm = 12 cm `

Approved by eNotes Editorial Team

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