An object is in free fall from a height of 80 m. How long will it take to reach

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Question: An object is in free fall from a height of 80 m. How long will it take to reach the ground? (g = 9.8 m/s²)

Options:

Correct Answer: 5 s

Solution:

Using the formula s = ut + 0.5gt², where u = 0, s = 80 m, and g = 9.8 m/s², we solve 80 = 0 + 0.5 * 9.8 * t², giving t ≈ 4.04 s.

An object is in free fall from a height of 80 m. How long will it take to reach the ground? (g = 9.8 m/s²)

An object is in free fall from a height of 80 m. How long will it take to reach the ground? (g = 9.8 m/s²)

Correct Answer: 4.04 seconds

Step 1: Identify the variables in the problem. We have the height (s) = 80 m, initial velocity (u) = 0 m/s (since the object is dropped), and acceleration due to gravity (g) = 9.8 m/s².
Step 2: Write down the formula for distance in free fall: s = ut + 0.5gt².
Step 3: Substitute the known values into the formula: 80 = 0 + 0.5 * 9.8 * t².
Step 4: Simplify the equation: 80 = 0.5 * 9.8 * t² becomes 80 = 4.9 * t².
Step 5: To isolate t², divide both sides by 4.9: t² = 80 / 4.9.
Step 6: Calculate the right side: t² ≈ 16.33.
Step 7: Take the square root of both sides to find t: t ≈ √16.33.
Step 8: Calculate the square root: t ≈ 4.04 seconds.

Free Fall – The motion of an object under the influence of gravity alone, with no other forces acting on it.
Kinematic Equations – Equations that describe the motion of objects, particularly under constant acceleration, such as the equation s = ut + 0.5gt².
Acceleration due to Gravity – The constant acceleration experienced by an object in free fall near the Earth's surface, approximately 9.8 m/s².