A monorail train starts from rest on a curve of radius 400 m and

accelerates at the constant rate a_t. If the maximum total acceleration

of the train must not exceed 1.5 m/s^2, determine (a) the shortest

distance in which the train can reach a speed of 72 km/h, (b) the

corresponding constant rate of acceleration a_t.

Respuesta :

Answer:

(a) Shortest distance traveled by train = 178.89 m

(b) Constant acceleration will be [tex]a_t=1.118m/sec^2[/tex]      

Explanation:

We have given speed v = 72 km /hr = [tex]=\frac{72\times 1000m}{3600sec}=20m/sec[/tex]

Radius of path = 400 m

Total acceleration [tex]a=1.5m/sec^2[/tex]

We know that normal acceleration is given by [tex]a_n=\frac{v^2}{r}=\frac{20^2}{400}=1m/sec^2[/tex]

(b) Total acceleration is given by [tex]a^2=a_n^2+a_t^2[/tex]

[tex]1.5^2=1^2+a_t^2[/tex]

[tex]a_t=1.118m/sec^2[/tex]

So corresponding acceleration will be [tex]a_t=1.118m/sec^2[/tex]

(a) As the train starts from rest its initial velocity u = 0 m/sec

Final velocity v = 20 m/sec

Acceleration [tex]a_t=1.118m/sec^2[/tex]

From third equation of motion we know that [tex]v^2=u^2+2as[/tex]

[tex]20^2=0^2+2\times 1.118\times s[/tex]

s = 178.89 m

Lanuel

The shortest distance in which the train can reach a speed of 72 km/h is equal to 178.89 meters.

Given the following data:

  • Initial speed = 0 m/s (since it's starting from rest).
  • Final speed = 72 km/h to m/s = 20 m/s.
  • Maximum total acceleration = 1.5 [tex]m/s^2[/tex].
  • Radius = 400 m.

How to calculate the shortest distance.

First of all, we would determine the centripetal acceleration of the train by using this formula:

[tex]A_v =\frac{V^2}{r} \\\\A_v =\frac{20^2}{400}\\\\A_v =\frac{400}{400}\\\\A_v =1\;m/s^2[/tex]

The maximum total acceleration experienced by the train is given by:

[tex]A_T^2 =A_v^2 +A_t^2\\\\1.5^2=1^2+A_t^2\\\\A_t=2.25-1\\\\A_t=\sqrt{1.25}\\\\A_t=1.118\;m/s^2[/tex]

For the shortest distance, we would apply the third equation of motion:

[tex]V^2 = U^2 +2aS\\\\20^2 = 0^2 +2(1.118)S\\\\400=2.236S\\\\S=\frac{400}{2.236}[/tex]

S = 178.89 meters.

Read more on distance here: brainly.com/question/10545161