I have understood all the parameters except Rds and conduction loss. Please explain them to me.

I am using a Lithium-Ion battery pack of 36 V and its maximum voltage is 42 V to drive a motor.

Motor specs:
minimum current : 500 mA
maximum current : 15 A
Ipulse : 30 A

The MOSFET I am planning to use is the Vishay SQD50N05-11L

MOSFET specs:

So based on the above specification, I have calculated the power dissipation:

Power dissipation: (i)^2 * Rds ---> (15A)^2 * 11 mohm = 2.47 watts

and the maximum power the transistor can dissipate without heat sink:

T(max) - T(ambient) / R(jA) ---> 175 - 25 / 60 = 2.5 watt

I am confused that how to check and relate the Power dissipation with Rds and select the MOSFET based on it.
Is the MOSFET that I have chosen okay, based on the above specs or should I go for a MOSFET with low Rds? And please explain how to select the MOSFETs based on Rds