The engine of a beach buggy develops 40 kW at a speed of 900 r/minutes.

The angular velocity is given by $\omega = 2 \pi N_{rev/s}$. This is the value for 's' in the context of angular speed.

$$\omega = 2 \pi \times 15 \text{ r/s}$$ $$\omega = 30 \pi \text{ rad/s}$$ $$\omega \approx 30 \times 3.14159 \text{ rad/s}$$ $$\omega \approx \boxed{\text{94.25 rad/s}}$$

The relationship between power, torque, and angular velocity is $P = T \omega$.

$$T = \frac{P}{\omega}$$ $$T = \frac{40000 \text{ W}}{30 \pi \text{ rad/s}}$$ $$T = \frac{40000}{30 \pi} \text{ N}\cdot\text{m}$$ $$T = \frac{4000}{3 \pi} \text{ N}\cdot\text{m}$$ $$T \approx \frac{4000}{3 \times 3.14159} \text{ N}\cdot\text{m}$$ $$T \approx \frac{4000}{9.42477} \text{ N}\cdot\text{m}$$ $$T \approx \boxed{\text{424.41 N}\cdot\text{m}}$$