Question

A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is:
(i) 100 km
(ii) 25 km
(iii) 15 km
(iv) 10 km
NCERT Solutions for Class 7th Science Chapter 13 Motion and Time Page 157 Exercise Question 10

Answer 1

we know that
       speed=distance/time
  or,    speed×Time =distance
here, a car run first by speed  40km/h and after 60km/h
 for first 15 min,
     speed=40km/h
     distance=?
    time=15/60 minute

then,  distance=40×15/60
           =4×15/6
          =60/6=10 km

for next 15 minute
  speed=60
  distance=?
  time=15/60

distance=60×15/60
            =60×1/4=15 km

 therefore,  total distance =25 km