The average** reaction time** of Gemma is 0.1564 seconds.

As we know, Gemma is catching the scale and Emily is dropping the scale.

The whole experiment is taking place under gravity, so the **acceleration **is constant.

As we know, the scale is dropped, it means that the initial velocity of the scale is zero.

We can use the **equation of motion,**

The equation is,

S = Ut + 1/2at²

Where,

S is the **displacement**, which is 0.12 m in our case,

U is **initial velocity** which is 0m/s because the stone is dropped,

t is the **time taken**, this is equal tot he reaction time here,

a is the **acceleration due to gravity** whose value is 9.8m/s.

Now, putting all the values,

0.12 = 1/2(9.8)(t)²

t² = 0.24/9.8

t = 0.1564 seconds.

Gemma reacts in 0.1564 seconds to catch the scale.

To know more about** equation of motion, **visit,

brainly.com/question/27821888

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