Average speed = (total distance covered) / (time to cover the distance)
Ian's total distance covered = (2km + 0.5km + 2.5km) = 5 km.
His time to cover the distance = 3 hours.
Average speed = (5 km) / (3 hrs)
Average speed = (5/3) (km/hr)
<em>Average speed = 1.67 km/hr</em>
<u>Answer:</u>
Positive acceleration is in third hour and negative acceleration is in second hour.
<u>Explanation:</u>
Velocity of car in first hour = 70 mph
Velocity of car in second hour = 60 mph
Velocity of car in third hour = 80 mph
Acceleration = Change in velocity / Time
Acceleration in second hour = (60 - 70)/1 = -10 mph²
Acceleration in third hour = (80 - 60)/1 = 20 mph²
So positive acceleration is in third hour and negative acceleration is in second hour.
Answer: B. water frozen in the cracks of a rock help to break down the rock because water expands when frozen, and physically forces the rock apart
The answer is has no moons. Mars has two moons
