The equation for the motion of the first car with respect to the Earth's surface is:

x₁ = v₁t + x₀

Where x₁ is the position of the car at time t, v₁ is the velocity of the car with respect to the Earth's surface, and x₀ is the initial position of the car.

The equation for the motion of the second car with respect to the first car is:

x₂ = v₂t + x₀

Where x₂ is the position of the second car at time t with respect to the first car, and v₂ is the velocity of the second car with respect to the first car.

To find the motion of the second car with respect to the Earth, we need to use the relative velocity formula:

v_{2, E} = v₂ + v_{1, E}

Where v_{2, E} is the velocity of the second car with respect to the Earth, and v_{1, E} is the velocity of the first car with respect to the Earth.

Since the velocity of the first car with respect to the Earth is given as 2 m/s along the x-axis, and the velocity of the second car with respect to the first car is not specified, we can use any value for v₂. Let's choose a value of 3 m/s along the y-axis, as this will result in a more interesting graph.

Thus, the velocity of the second car with respect to the Earth is:

v_{2, E} = (0, 3) m/s

This means that the velocity of the second car with respect to the Earth has a magnitude of 3 m/s and a direction of 90°, or directly above the first car's position.

Now, we can use this velocity in the equation for the motion of the second car with respect to the Earth:

x_{2, E} = v_{2, E}t + x₀

Since the initial position of the second car is the same as the initial position of the first car, we can set x₀ as 0.

Therefore, the equation for the motion of the second car with respect to the Earth is:

x_{2, E} = 3t

This is the graph of the second car's motion in the Earth's reference frame, with the origin at the initial position of the first car.

To graph the first car's motion in the Earth's reference frame, we can simply use its original velocity, which is 2 m/s along the x-axis. The equation for its motion is:

x_{1, E} = 2t

This results in a graph with a slope of 2, or a straight line.