Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class

NCERT Questions

NCERT Question 1
Important

NCERT Question 2 Important

NCERT Question 3 Important

NCERT Question 4 Important

NCERT Question 5 Important

NCERT Question 6 Important

NCERT Question 7 Important You are here

NCERT Question 8

NCERT Question 9

NCERT Question 10 Important

NCERT Question 11 Deleted for CBSE Board 2024 Exams

NCERT Question 12 Important

NCERT Question 13

NCERT Question 14

NCERT Question 15 Important

NCERT Question 16 Important

NCERT Question 17 Important

NCERT Question 18 Important

Class 9

Chapter 9 Class 9 - Force and Laws Of Motion

Last updated at May 29, 2023 by Teachoo

NCERT Question 7 A 8000 kg engine pulls a train of 5 wagons, each of 2000 kg, along a horizontal track. If the engine exerts a force of 40000 N and the track offers a friction force of 5000 N, then calculate: Mass of engine = 8000 kg Mass of 1 wagon = 2000 kg Mass of 5 wagons = 5 × 2000 = 10, 000 kg Force exerted by engine = 40,000 N Force of friction = 5000 N (a) the net accelerating force and Net Force = Force of engine − Force of friction = 40000 − 5000 = 35000 N (b) the acceleration of the train. We know that Force = mass × acceleration We have found Force in the last part Force = 35000 N Mass = Total Mass = Mass of Engine + Mass of 5 wagons = 8000 + 10000 = 18000 Now, F = M × a 35000 = 18000 × a a = 35000/18000 a = 1.944 m/s2 Thus, acceleration of train is 1.944 m/s2