Question

you slide a hockey puck across the ice in a hockey rink the puck gradually slows down as it moves how does newtons first law explain the motion of the puck

Answer 1

It explains it becuase it was acted on by an outside force being the ice and friction.

Step-by-step explanation:

Like stated above an object in motion stays in motion unless acted upon by an outside force. In this scenaro it was the ice and the puck causing friction and it finally stopping.

Answer 2

"An object in motion tends to remain in motion UNLESS acted on by an external force" {emphasis on UNLESS}

In the case of a puck sliding across the ice: it slows (decelerates) because of the friction force between ice and puck. THIS friction force IS the external force spoken about in the 1st Law, above...and...thus is the reason the puck eventually stops moving.