A spur gear with $20^{\circ}$ full depth teeth is transmitting $20 \: kW$ at $200 \: rad/s$. The pitch circle diameter of the gear is $100 \: mm$. The magnitude of the force applied on the gear in the radial direction is

- $0.36 \: kN$
- $0.73 \: kN$
- $1.39 \: kN$
- $2.78 \: kN$