Question

Figure 1.18 (Chapter 1) shows the Hoover Dam Bridge over

Answer 1

Answer: 7.436 s

Explanation:

This situation is related to vertical motion, specifically free fall and can be modelled by the following equation:

$y=y_{o}+V_{o} t+\frac{gt^{2}}{2}$  

Where:

$y= 0m$ is the final height of the object (when it makes splash)

$y_{o}=271 m$  is the initial height of the object

$V_{o}=0 m/s$  is the initial velocity of the object (it was dropped)

$g=-9.8m/s^{2}$  is the acceleration due gravity (directed downwards)

$t$ is the time since the objecct is dropped until it makes splash

$0=y_{o}+0+\frac{gt^{2}}{2}$  

Clearing $t$:

$t=\sqrt{\frac{-2y_{o}}{g}}$  

$t=\sqrt{\frac{-2(271 m)}{-9.8m/s^{2}}}$  

Finally:

$t=7.436 s$