Answer:
F = 0 N
Step-by-step explanation:
Force on a moving charge in constant magnetic field is given by the formula
![F = q(\vec v* \vec B)](https://img.qammunity.org/2020/formulas/physics/high-school/ttx9xka4etw4e7h166w9oy6j04tnoky8y7.png)
so here it depends on the speed of charge, magnetic field and the angle between velocity of charge and the magnetic field
here when charge is moving with speed 100 m/s in a given magnetic field then the force on the charge is given as
![F = 4 N](https://img.qammunity.org/2020/formulas/physics/high-school/44n0zc4yx1fnbpp9llyn56sds0qybtw40d.png)
now when charge is moving parallel to the magnetic field with different speed then in that case
![\vec v \time \vec B = 0](https://img.qammunity.org/2020/formulas/physics/high-school/7iuf8j4elld83mi6c3sn9m0nxw17odkyn6.png)
so here we have
F = 0