* Work done, $W = 30000 \text{ J}$

* Distance moved, $d = 20 \text{ m}$

To find:

* Force applied, $F$

Solution:

The force applied to the boulder can be calculated using the formula:

$$W = F \times d$$

Where:

* $W$ is the work done

* $F$ is the force applied

* $d$ is the distance moved

Substituting the given values into the formula, we get:

$$30000 \text{ J} = F \times 20 \text{ m}$$

Dividing both sides by $20 \text{ m}$, we get:

$$F = \frac{30000 \text{ J}}{20 \text{ m}}$$

$$F = 1500 \text{ N}$$

Therefore, the force applied to the boulder is 1500 N.