2. Questions Bank
  3. 7th Class
  4. Science
  5. Time and Motion

7th Class Science Time and Motion Question Bank Motion and Time

  • question_answer
    A body covers half of its journey with a speed of 60 m/s and the other half with a speed of 40 m/s. Then average speed during whole journey is

    A) 0                                 

    B) 50 m/s

    C) 48 m/s       

    D) 52 m/s

    Correct Answer: C

    Solution :

        Let the total distance be 100 m. Then time taken to complete half (50m) at \[60m/s=\frac{50}{60}s\] time taken to complete half \[(50m)\]at \[40m/s=\frac{50}{40}s\] Total time taken\[=\left( \frac{50}{60}+\frac{50}{40} \right)s=\frac{25}{12}s\] Average speed\[=\frac{100}{\frac{25}{12}}\] Or        \[\frac{100}{25}\times 12=48m/s\]  


You need to login to perform this action.
You will be redirected in 3 sec spinner