1. two forces of 7 lb. and 14 lb. act on a body at right angles to each other. find the angle their resultant force makes with the force of 14 lb.

2.a velocity of 30 mph is resolved into two components, each of which makes an angle of 45 with it. find their magnitude.

1.  26.6°

2. 21.2 mph each

Explanation:

1. When two forces are acting perpendicular to each other, then their resultant is given by:

R = √(F²+F'²+ 2 F F' cosθ) =√(7²+14²+ 2×7×14 cos 90°) = 15.65.

Angle between two vectors can be found using law of sines:

We have to find the angle (Ф) opposite side 7 lb force i.e. angle between Resultant and 14 lb force.

2.

Let the components of velocity be v and v'

Because each component makes an angle 45° with the resultant, it can be found as:

v = 30 cos 45° = 21.2 mph

v' = 30 cos 45° = 21.2 mph

Both the components would be equal in magnitude.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it