A train is moving on a railway track at a speed of 100 km/hr. The brakes are applied and after 40 s the speed decreases by 10 %. The detardation of the train is proportional to the velocity of the train. Determine the velocity of the train in km/hr at the time period of 120 s.
Answers
Answered by
1
Answer:
The speed of the train 120 seconds will be 70 km/h
Explanation:
We need to calculate the retardation in 40s.
The speed decreases by 10%.
10% of 100km/h = 10/100 × 100 =
10 km/h
We convert the time to hours = 40/3600 = 1/90 hours
Retardation = change in speed / time
= 10 × 90 = 900 km/h²
Now given:
u = 100 km/h
t = 120s = 120/3600 = 1/30 hrs
a = 900km/h²
We will apply kinematics equation to get the final velocity.
V = u - at
Substituting we have :
V = 100 - 900 × 1/30
V = 100 - 30 = 70 km/h
After 120 seconds the speed will be 70 km/h
Similar questions