Given →a+→b+→c+→d=0, which one of the following is incorrect?
1. | →a, →b, →c and →d must be null vectors. |
2. | The magnitude of →a+→c equals the magnitude of →b+→d. |
3. | The magnitude of →a can never be greater than the sum of the magnitudes of →b,→c and →d. |
4. | →b+→c must lie in the plane of →a and →d if →a and →d are not collinear, and along the direction of →a and →d if they are collinear. |
A scalar quantity is one that:
1. | is conserved in a process. |
2. | will never accept negative values. |
3. | must be dimensionless. |
4. | has the same value for observers with different orientations of axes. |