A car drives 10km with a speed of 72 km/hr and then runs out of gas. Then you walk 2km for the next 30 min until you find a gas station. (A) What is the displacement of the total trip? (B) How long does the entire trip take? (C) What is the average velocity of the entire trip?

(A) Total Displacement = 12 km

(B) t = 38.33 min

(C) Average Velocity = 18.8 km/h

Explanation:

(A)

The displacement of the trip is the sum of both distances:

Total Displacement = 10 km + 2 km

Total Displacement  = 12 km

(B)

First we calculate the time taken by the car:

s = vt

where,

s = distance covered by car = 10 km

v = speed of car = 72 km/h

t = time taken = ?

Therefore,

t = (10 km)/(72 km/h)

t = (0.139 h)(60 min/1 h)

t = 8.33 min

now, we add the 40 min of walking in this:

t = 8.33 min + 30 min

t = 38.33 min

(C)

The average velocity is given as:

Average Velocity = Total Displacement/t = (12 km/38.33 min)(60 min/1 h)

Average Velocity = 18.8 km/h

radiation

explanation:

heat is transmitted by radiation