How do you calculate the acceleration of gravity?

1. By performing an experiment.

2. By calculating it using law of gravitation.

Explanation:

Method 1:

Step 1: First you need a timer, a ball and a smart phone with camera.

Step 2: Go to, say, third floor of your school building, drop the ball and start the timer.

Step 3: Take a shot every 1 second until the ball reaches the ground.

Step 4: Check your photo. Pay attention to where it reaches at every second. Try to measure the distance it goes from the top. Ex: t = 1, d = ?, t = 2, d = ? ...

Step 5: Since velocity = distance / time, now you can calculate like v1 = d1 / t1, v2 = d2 / t2 ...

Step 6: Since acceleration = velocity / time, now you can calculate a1 = v1 / t1, a2 = v2 / t2 ...

Step 7: Repeat this measurement for several times, and you'll find the average acceleration of gravity to be nearly 9.8 m/s^2.

Method 2:

We can simply apply the equation for getting the acceleration of gravity:

g =  GM/r^2,

where G is the gravitational constant, M is the mass of Earth, r is the radius of Earth (since you probably need to know the acceleration of gravity near the surface of Earth).

Let's plug numbers in:

g =

Try to calculate this, and you will get that g = 9.8 m/s^2.