Physics Free Fall Explained- Video Tutorial and Examples

What Is Free Fall in Physics?

Free fall is when an object moves under gravity's sole influence. No air resistance. No propulsion. Just the pull of Earth pulling it downward.

That's it. Nothing fancy.

Drop a ball off a building, and it's in free fall the second it leaves your hand. Throw a baseball sideways—it's still in free fall. The horizontal motion doesn't change the vertical physics.

The Core Physics: What Actually Happens

Every object near Earth's surface accelerates at 9.8 m/s². This is the acceleration due to gravity, represented by the symbol g.

This means:

• After 1 second: velocity = 9.8 m/s
• After 2 seconds: velocity = 19.6 m/s
• After 3 seconds: velocity = 29.4 m/s

The object speeds up by 9.8 meters per second every single second. It's constant acceleration—Newton's second law working exactly as expected.

The Key Equations

You'll use these three equations for any free fall problem:

Equation 1: Velocity

v = g × t

v = final velocity, g = 9.8 m/s², t = time in seconds

Equation 2: Distance

d = ½ × g × t²

d = distance fallen, g = 9.8 m/s², t = time in seconds

Equation 3: Velocity and Distance Combined

v² = 2 × g × d

Useful when you know velocity but need distance, or vice versa

Free Fall vs. Regular Falling: What's the Difference?

In real life, air resistance slows falling objects. A feather falls slowly. A bowling ball falls fast.

But in ideal physics free fall, we ignore air resistance. This isn't being lazy—it's making the problem solvable. Once you understand the ideal case, you can add air resistance back in.

The difference matters:

Real Examples of Free Fall

Here are situations where free fall physics applies:

• Dropping a ball from rest
• A skydiver before deploying parachute (technically still experiences air resistance, but close)
• A rocket with engines off, coasting in space
• Dropping something from a roof

Notice I didn't include a parachute skydiver falling at terminal velocity. That's not free fall—air resistance is doing significant work.

Common Mistakes Students Make

1. Forgetting that "down" is negative. If upward is positive, then gravity is -9.8 m/s². Sign matters.

2. Using the wrong equation. Students often reach for v² = 2gd when they should use d = ½gt². Know which variables you have and which you need.

3. Confusing velocity with acceleration. Velocity increases. Acceleration is constant. At 5 seconds, velocity is 49 m/s. Acceleration is still 9.8 m/s².

4. Ignoring initial conditions. If you throw something downward, its initial velocity isn't zero. The equation changes: v = g×t + v₀

Getting Started: How to Solve Free Fall Problems

Here's the process that actually works:

Step 1: Define Your Coordinate System

Pick "up" as positive or "down" as positive. Write it down. Stay consistent.

Step 2: List What You Know

Write down: initial velocity, time, distance, final velocity. Circle what you're solving for.

Step 3: Pick the Right Equation

If you have time and need distance → d = ½gt²

If you have velocity and need time → v = gt

If you have velocity and need distance → v² = 2gd

Step 4: Plug In and Solve

Use g = 9.8 m/s². Watch your units. Show your work.

Step 5: Check Your Answer

Does the number make sense? A fall of 5 meters takes about 1 second. A fall of 100 meters takes about 4.5 seconds. If your answer doesn't match reality, you made an error.

Quick Example Problem

Question: A rock falls from a cliff. How far does it fall in 3 seconds?

Solution:

d = ½ × 9.8 × 3²

d = ½ × 9.8 × 9

d = 44.1 meters

Question: What velocity does it reach?

v = 9.8 × 3 = 29.4 m/s

That's roughly 65 mph. A rock hitting you at that speed would ruin your day.

The Bottom Line

Free fall physics isn't complicated. Gravity accelerates everything at 9.8 m/s². Use the right equation. Watch your signs. Solve for what you need.

Most free fall problems are straightforward once you stop overthinking them. The math is simple arithmetic. The hard part is setting up the problem correctly.

Master the basics above, and you'll handle any free fall question they throw at you.