# Calculate force needed to reach certain point (AddForce)

Hello everyone, So I have the following system setup for an arrow shooting game:

A force (from 0 to a certain maximum value) is chosen by the player. Say force is F.

The angle (from 0 to 90) is also chosen by the player. Say degrees are D.

Afterwards, having the force and degrees, AddForce is used. Two forces are applied - one for X, and one for Y. F_Y is calculated like this: F * (D / 90f), and F_X = F - F_Y. Thus the force added is AddForce(F_X, F_Y)

The Arrow is fired. Gravity value is default. Arrows may have different weights (rigidbody). Distance between the starting position and end position are given.

I need a way to figure out the total force or just one of the forces needed to reach a SPECIFIC point (X and Y, Z axis is not used at all). I am aware that there are multiple X & Y possibilities, however, is there a way to know at least one of the forces (or the total) having only the following variables? (I need to find out this value in a script for different degree, distance and arrow weight values)

Thank you!

**Answer** by sysmaya
·
Jul 04, 2017 at 11:12 PM

This function calculate the Vector3 and speed for parabolic shoots. EJ: Shoot Bows, Shoot canons, etc.

```
Vector3 calcBallisticVelocityVector(Vector3 source, Vector3 target, float angle){
Vector3 direction = target - source;
float h = direction.y;
direction.y = 0;
float distance = direction.magnitude;
float a = angle * Mathf.Deg2Rad;
direction.y = distance * Mathf.Tan(a);
distance += h/Mathf.Tan(a);
// calculate velocity
float velocity = Mathf.Sqrt(distance * Physics.gravity.magnitude / Mathf.Sin(2*a));
return velocity * direction.normalized;
}
```

Hello, Sorry to Necro the thread. Does this factor in the mass of the object being launched? Or is it assumed the mass is 1?

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