Question

The relative velocity of two trains travelling in opposite directions is calculated by adding their velocities. In case, the trains are travelling in the same direction, the relative velocity is the difference between their velocities. Write a program to input the velocities and length of the trains. Write a menu driven program to calculate the relative velocities and the time taken to cross each other.

Answer 1

import java.util.*;
public class Q13
{public static void main(String acp[])
{Scanner ob = new Scanner(System.in);
float v1, v2, len1, len2, rvel = 0, time = 0; int dir; 
System.out.printin("Enter the velocities of the trains in metres / second");
v1 = ob.nextFloat();
v2 = ob.nextFloat();
System.out printin("Enter the lengths of the trains in metres");
len1 = ob.nextFloat();
len2 = ob.nextFloat();
System.out.println("Enter 1 for same direction or 2 for opposite direction");
dir = ob.nextInt();
switch(dir)
{case 1: rvel = Math.abs (v1 − v2);
time = (len1 -+ len2) / rvel;
break; 
case 2: rvel = v1 + v2;
time = (len1 + len2) / rvel;
break;
default: System.out.println("Invalid entry!");
}
System. out.println("Relative velocity of the trains: " + rvel + " m/s");
System.out.printIn("Time taken for the trains to cross each other: " + time + "s");
}}