Answer:
A plain mirrior is a mirrior with flat reflective surface.
hope it is helpful for you.
The law says things travel in a straight line at constant speed unless acted upon by a force. But friction is a force but it can't be seen easily other than its effect, which is to bring the object to rest in seeming violation of the 1st law.
~686newtons on earth and
~1617 newtons on jupiter
the formula is weight = gravitational acceleration * mass of the object
