A hiker accidentally knocks a rock off the edge of a steep cliff. Assuming there is no air… — Armed Services Vocational Aptitude Battery (ASVAB)

A hiker accidentally knocks a rock off the edge of a steep cliff. Assuming there is no air resistance and the acceleration due to gravity is $10\text{ m/s}^2$ , how fast is the rock traveling exactly $3$ seconds after it begins to fall?

Answer: 30 m/s

Answer

In free fall with no air resistance, an object's speed increases by the acceleration of gravity each second. After

3

seconds of accelerating at

10\text{ m/s}^2

, the speed is exactly

30\text{ m/s}

Step-by-Step Solution

Identify the relevant formula

v = gt

The rock starts from rest, so its speed depends only on gravitational acceleration multiplied by the elapsed time.

Substitute the given values into the formula

v = 10 \times 3 = 30

Gravity accelerates the object by

10\text{ m/s}^2

for every second it falls.

Key Concept

Velocity of an object in free fall increases linearly with time based on gravitational acceleration.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic