If objects are traveling in opposite directions, what do you know about the signs of their momenta?

Acar accelerates from 5.0 m/s to to 11 m/s at a rate of 3.0 m/s^2. how far does it travel while accelerating? 20m 117m 43m 16m

A500g object falls off a cliff and losers 100 j from its gravitational potential energy store. if the gravitational field strength g=9.8n/kg, how high is the cliff?

What property is a characteristic of a substance that can be observed and does not change the identity of the substance