Question

olivia is taking pictures of the ocean on the edge of a cliff when she accidentally drops her phone. The phone hits the water at a vertical velocity of 15.75m/s and landed 16m away from the base of the cliff. how tall is the cliff?

Answer 1

The cliff is 12.71m tall.

Why?

Before solving the problem, we must remember that the phone was dropped, it means that there is no initial velocity, also, the acceleration acting on the phone is the acceleration due to gravity.

So, to find how tall is the cliff, we can use the following equations:

$y=y_o+v_o*t-\frac{1}{2}g*t^{2}\\\\v_f=v_o+g*t$

$t=\frac{v_f}{g} \\\\t=\frac{-15.75\frac{m}{s}}{-9.81\frac{m}{s^{2}}}=1.61s$

Now that we know the time, we can calculate how tall is the cliff:

$y=y_o+v_o*t+\frac{1}{2}g*t^{2}\\\\y=0+0*1.61s-\frac{1}{2}*(-9.81\frac{m}{s^{2}})*(1.61s)^{2}\\\\y=12.71m$

Hence, we have that the cliff is 12.71m tall.

Have a nice day!