Question

a car travels with speed 30 km h-1 for 30 minutes and then with speed 40 km h-1 for 1 hour find: the total distance travelled by the car , the total time of travel , and the average speed of car ​

Answer 1

Step-by-step explanation:

Speed of car for first 30 minutes = 30 km h-1

Speed of car for next 1 hour = 40 km h-1

(a) Total distance travelled by the car

1st case, speed = Distance/Time ⇒ Distance = Speed × Time

(∵ 30 minutes = 0.5 hours)

Distance = 30 × 0.5

= 15 km ……(i)

IInd case Speed = Distance/Time ⇒ Distance = Speed × Time

Distance = 40 km h-1 × 1 hr

= 40 km …………(ii)

Adding (i) and (ii)

Total Distance = 15 km + 40 km = 55 km

(b) Total time of travel = 0.5 hr + 1.0 hrs = 1.5 hr

(c) Average speed = Total distance travelled/Total time taken

= 5.5 km/1.5 hr [from above (a) and (b)]

= 36.67 km h-1

Answer 2

Answer:

First case:

Speed (S)= 30Km/hr

Time (T)= 30 mins= 1/2 hr

So, Distance (D)= S×T= 30×1/2= 15 Km

Second case:

S= 40Km/hr

T= 1hr

so, D= S×T = 40×1 = 40km

total distance= (15+40)km = 55km

total time= 1hr30mins= 1.5 hr

average speed= total distance÷total time= 55km÷1.5hr= 36.66Km/hr