Answer:
8 m/s
Explanation:
All you have to do here is add 20 and 60 (giving you 80) and dividing by 10 seconds. 80/10= 8 m/s
The car heads east at an average speed of 50 miles per hour from the intersection point towards East. The truck heads east at an average speed of 60 miles per hour from the intersection point towards South.
The distance of car from the intersection point after t hours is
.
The distance of truck from the intersection point after t hours is
.
Since these distances are perpendicular to each other, distance apart d (in miles) at the end of t hours is

Thus the distance apart is 
Distance, since distance represents how far something has travelled, which would be in our case 2.5m.
Answer:
mass.
Explanation:
other physical factors are changeable but the mass of a particular substance is always constant.