Suppose a rock fell off a cliff. After 5 seconds, its speed well be 100 m/s

false

V would be g*t = 49 m/s

To calculate the height of the cliff, we need to use the equation of motion.

The equation of motion for an object falling under the influence of gravity is:

y = y₀ + v₀t + (1/2)gt²

where:
y is the height of the object at time t,
y₀ is the initial height (the top of the cliff),
v₀ is the initial velocity (which is 0 since the rock starts from rest),
t is the time (which is 5 seconds in this case),
g is the acceleration due to gravity (approximately 9.8 m/s²).

Plugging in the values:
y = y₀ + v₀t + (1/2)gt²
y = y₀ + 0 + (1/2)(9.8)(5)²
y = y₀ + 0 + (1/2)(9.8)(25)
y = y₀ + (1/2)(9.8)(25)
y = y₀ + (1/2)(245)
y = y₀ + 122.5

Therefore, the height of the cliff is y₀ + 122.5 meters. We would need to know the initial height (y₀) to calculate the exact height, but the additional information given is not enough for that calculation.