-- The total distance between the towns = 460 km.
-- For the first 3 hours, he travels at an average speed of 60 km/hr. During that time, he covers (60 km/hr) x (3 hrs) = 180 km.
-- At that point, he still has (460km - 180km) = 280 km to go.
-- If he drives that 280km at an average speed of 70 km/hr, it'll take him (280km)/(70km/hr) = 4 hrs to cover it.
-- His total time for the whole trip is (3 hours for the first part) + (4 hours for the last part) = <em>7 hours</em>.
To reduce the internal energy U of an ideal gas you need the gas to lose heat and/or do work.
When the velocity increases, then the acceleration will be positive and when the velocity decrease then the acceleration will be negative.
During the first hour, the velocity was 70 mph and during the seconds hour the velocity was 60 mph. Hence, the velocity decrease in the seconds hour. So, the acceleration will be negative during the second hour.
Now, during the third hour the velocity increases as it is 80 mph. Hence, the acceleration will be positive during the third hour.
Place mixtuer into water. stir mixture into water, wait untill salt is disoldved. Strain out grain. boil water intill only salt is left. Hope this helps! ^-^
1) Sleeping with an electronic in charge right next to you.
2) Leaving a charger plugged in all the time especially near liquid substances.
