A dart leaves the barrel of a blowgun at a speed $v$ . The length of the blowgun barrel is $L$ . Assume that the acceleration of the dart in the barrel is uniform.
a. Show that the dart moves inside the barrel for a time of 2$L / v .$
b. If the dart's exit speed is 15.0 $\mathrm{m} / \mathrm{s}$ and the length of the blowgun is $1.4 \mathrm{m},$ show that the time the dart is in the barrel is 0.19 s.