The wagon with the mass m = 340 kg detached from the moving train and stop after the distance s = 50m with the uniform deceleration.
The wagon stopped after the time t =20 s
Find the friction force, the effective coefficient of friction and the initial train speed
Answers
The wagon with the mass m = 340 kg detached from the moving train and stop after the distance s = 50m with the uniform deceleration.
The wagon stopped after the time t =20 s
Find the friction force, the effective coefficient of friction and the initial train speed
Answer:
Answer:
- The train crosses the pole in 9 seconds. This means that from the point when the engine or the front of the train crosses the pole to the point when the back of the train reaches the pole, we have 9 seconds. Thus we can get the length of the train by calculating the distance that the train travels in 9 seconds.
We have the speed of the train = 60 km/hr. We have to convert it into m/s. Let us see the trick to convert km/hr to m/s:
1km/1h = 1×(1000/60×60) = 1×(5/18) m/s.
Therefore if the speed is ‘x’ km/hr then we can change it to m/s by multiplying x with 5/18. Let us do it for the current example.
We have the speed of the train = 60 km/hr or 60×(5/18) = 50/3 m/s.
Therefore in 9 seconds, the train will cover a distance = speed×time
In other words, we have the Distance = (50/3 m/s)×9 = 150 m. Therefore the correct option is D) 150 meters. Let us see some more examples that can be formulated on the basis of this concept.