Final answer:
To find the speed at which the rock was thrown, we can use the equations of motion. Since the rock was thrown horizontally, its initial vertical velocity is zero.
Step-by-step explanation:
To find the speed at which the rock was thrown, we can use the equations of motion. Since the rock was thrown horizontally, its initial vertical velocity is zero. Using the equation for vertical displacement, we can find the time it takes for the rock to fall from the cliff to the ground:
d = (1/2) * g * t^2
where d is the vertical displacement, g is the acceleration due to gravity (approximately 9.8 m/s^2), and t is the time. Solving for t, we get:
t = sqrt(2 * d / g)
Substituting the given values of d = 150.0 m and g = 9.8 m/s^2, we can calculate t. Once we have t, we can use the equation for horizontal displacement to find the initial horizontal velocity:
v = d / t
Substituting the given values of d = 120.0 m and t, we can calculate v to find the speed at which the rock was thrown.