Final answer:
To calculate the height of the cliff, we can use the equation of motion: y = yo + vot - 1/2gt², where y is the height, yo is the initial position, vo is the initial velocity, t is the time, and g is the acceleration due to gravity.
Step-by-step explanation:
To calculate the height of the cliff, we can use the equation of motion: y = yo + vot - 1/2gt², where y is the height, yo is the initial position, vo is the initial velocity, t is the time, and g is the acceleration due to gravity.
In this case, the initial position yo is 0, the initial velocity vo is 0 (since Alvin jumps from rest), and the acceleration due to gravity g is 9.8 m/s².
Plugging in the values, we have: y = 0 + 0*t - 1/2*9.8*t².
Since it took Alvin 2.8 seconds to hit the water, we can substitute t with 2.8 and solve for y to find the height of the cliff.
Therefore, the height of the cliff is approximately 38.7 meters.