The magnetic force (Lorentz force) experienced by the proton in the magnetic field is given by

since

, because the velocity v and the force F in this problem are perpendicular, and so also the angle

between the velocity and the magnetic field B should be

.
Let's find the magnitude of the magnetic field; this is given by

To understand the direction, let's use the right-hand rule:
-index finger: velocity
- middle finger: magnetic field
- thumb: force
Since the velocity (index) points east and the force (thumb) points south, then the magnetic field (middle finger) points downwards. So we write:
B = -0.091 T
Answer:

Explanation:
The frequency of a light is inversely proportional to its wavelength. It is given by:

The speed of the red light, v = 3.0 × 10⁸ m/s
The wavelength of the red light, λ = 690 nm = 690 ×10⁻⁹ m

Thus, the frequency of red light emitted by neon sign having wavelength 690 nm is 
Answer:
a) F = 35.7 N, b) W = 846.7 J, c) W = - 846.9 J, d) W=0
Explanation:
a) For this exercise let's use Newton's second law, let's set a reference frame with the x-axis horizontally
let's break down the pushing force.
cos (-23,7) = Fₓ / F
sin (-237) = F_y / F
Fₓ = F cos 23.7 = F 0.916
F_y = F sin (-23.7) = - F 0.402
Y axis
N- W - F_y = 0
N = W + F 0.402
X axis
Fₓ - fr = 0
F 0.916 = fr
F = fr / 0.916
F = 32.7 / 0.916
F = 35.7 N
It is asked to calculate several jobs
b) the work of the pushing force
W = fx x
W = 35.7 cos 23.7 25.9
W = 846.7 J
c) friction force work
W = F x cos tea
friction force opposes movement
W = - fr x
W = - 32.7 25.9
W = - 846.9 J
d) The work of the force would gravitate, as the displacement and the force of gravity are at 90º, the work is zero
W = 0