The amount of force needed to keep a 0.2 kg hockey puck moving at a constant speed of 8m/s on friction less ice is n

If there is really no friction and no air resistance, then NO force is needed to keep an object moving in a straight line at constant speed.  Check out Newton's first law of motion again.

F = 0 N

Explanation:

Given that,

Mass of the hockey puck, m = 0.2 kg

Speed of hockey puck, v = 8 m/s

As the speed is constant. So, there is no change in the velocity. As a result, the acceleration of the hockey puck is 0. Force is given by :

Since, a = 0

F = 0

So, the amount of force needed to keep a 0.2 kg hockey puck moving at a constant speed of 8 m/s on friction less ice is zero newton.