Complete question:
At a particular instant, an electron is located at point (P) in a region of space with a uniform magnetic field that is directed vertically and has a magnitude of 3.47 mT. The electron's velocity at that instant is purely horizontal with a magnitude of 2×10⁵ m/s then how long will it take for the particle to pass through point (P) again? Give your answer in nanoseconds.
[<em>Assume that this experiment takes place in deep space so that the effect of gravity is negligible.</em>]
Answer:
The time it will take the particle to pass through point (P) again is 1.639 ns.
Explanation:
F = qvB
Also;
![F = \frac{MV}{t}](https://tex.z-dn.net/?f=F%20%3D%20%5Cfrac%7BMV%7D%7Bt%7D)
solving this two equations together;
![\frac{MV}{t} = qVB\\\\t = \frac{MV}{qVB} = \frac{M}{qB}](https://tex.z-dn.net/?f=%5Cfrac%7BMV%7D%7Bt%7D%20%3D%20qVB%5C%5C%5C%5Ct%20%3D%20%5Cfrac%7BMV%7D%7BqVB%7D%20%3D%20%5Cfrac%7BM%7D%7BqB%7D)
where;
m is the mass of electron = 9.11 x 10⁻³¹ kg
q is the charge of electron = 1.602 x 10⁻¹⁹ C
B is the strength of the magnetic field = 3.47 x 10⁻³ T
substitute these values and solve for t
![t = \frac{M}{qB} = \frac{9.11 *10^{-31}}{1.602*10^{-19}*3.47*10^{-3}} = 1.639 *10^{-9} \ s \ = 1.639 \ ns](https://tex.z-dn.net/?f=t%20%3D%20%5Cfrac%7BM%7D%7BqB%7D%20%3D%20%5Cfrac%7B9.11%20%2A10%5E%7B-31%7D%7D%7B1.602%2A10%5E%7B-19%7D%2A3.47%2A10%5E%7B-3%7D%7D%20%3D%201.639%20%2A10%5E%7B-9%7D%20%20%5C%20s%20%5C%20%3D%201.639%20%5C%20ns)
Therefore, the time it will take the particle to pass through point (P) again is 1.639 ns.
They expend more oxygen. Littler endotherms lose warmth to the earth proportionately speedier than huge endotherms: less warm mass, protecting layers in littler creatures are less successful by dint of being more slender, and more prominent surface region to volume proportion implies snappier radiation of warmth
The initial kinetic energy of the boat and its rider is
![K_i = \frac{1}{2} mv_i^2 = \frac{1}{2}(900 kg)(1.4 m/s)^2=882 J](https://tex.z-dn.net/?f=K_i%20%3D%20%20%5Cfrac%7B1%7D%7B2%7D%20mv_i%5E2%20%3D%20%20%5Cfrac%7B1%7D%7B2%7D%28900%20kg%29%281.4%20m%2Fs%29%5E2%3D882%20J%20%20%20)
After Sam stops it, the final kinetic energy of the boat+rider is
![K_f = 0 J](https://tex.z-dn.net/?f=K_f%20%3D%200%20J)
because its final velocity is zero.
For the law of conservation of energy, the work done by Sam is the variation of kinetic energy of the system:
![W=K_f-K_i =0-882 J=-882 J](https://tex.z-dn.net/?f=W%3DK_f-K_i%20%3D0-882%20J%3D-882%20J)
where the negative sign is due to the fact that the force Sam is applying goes against the direction of motion of the boat.
Explanation:
That`s is the answer, just check
The answer should be C) Slide against each other.