Suppose that you are going to program a computer to carry out an iterative calculation of motion involving nonconstant forces. Which of the following calculations should be done before starting the repetitive "loop" calculations? Specify the initial (vector) momentum of each object. Define constants such as \( G \). Specify an appropriate value for the time step. Specify the initial (vector) position of each object. Update the (vector) position of each object.

Before starting the repetitive "loop" calculations in an iterative simulation of motion involving nonconstant forces, you should perform the following calculations: 1. **Specify the initial (vector) position of each object.** - This is essential as it sets the starting point for the simulation. 2. **Specify the initial (vector) momentum of each object.** - This is important to determine the initial state of motion for each object. 3. **Define constants such as \( G \).** - Constants that govern the forces acting on the objects (like gravitational constant \( G \)) need to be defined before the loop starts. 4. **Specify an appropriate value for the time step.** - The time step is crucial for the accuracy and stability of the simulation, and it should be set before entering the loop. The only calculation that should not be done before starting the loop is: - **Update the (vector) position of each object.** - This is part of the iterative process and should be done within the loop after calculating the forces and updating the momentum. In summary, the calculations that should be done before starting the loop are: - Specify the initial (vector) position of each object. - Specify the initial (vector) momentum of each object. - Define constants such as \( G \). - Specify an appropriate value for the time step.