Answer:
Explanation:
The force exerted in a magnetic field is given as
F = q (v × B)
Where
F is the force entered
q is the charge
v is the velocity
B is the magnetic field
Given that,
The magnetic field is
B = 2•i + 4•j. T
The velocity of the electron is
v = 2•i + 6•j + 8•k. m/s
Also, the charge of an electron is
q = -1.602 × 10^-19 C.
Then note that,
V×B is the cross product of the speed and the magnetic field
Then,
F = q (V×B)
F = -1.602 × 10^-19( 2•i + 4•j +8•k × 2•i + 4•j)
Note
i×i=j×j×k×k=0
i×j=k. j×i=-k
j×k=i. k×j=-i
k×i=j. i×k=-j
F = -1.602 × 10^-19[(2•i + 4•j +8•k) × (2•i + 4•j)]
F = -1.602 × 10^-19 [2×2•(i×i) + 2×4•(i×j) + 4×2•(j×i) + 4×4•(j×j) + 8×2•(k×i) + 8×4•(k×j)]
F = -1.602 × 10^-19[4•0 + 8•k + 8•-k + 16•0 + 16•j + 32•-i]
F = -1.602 × 10^-19(0 + 8•k - 8•k + 0 + 16•j - 32•i)
F = -1.602 × 10^-19(16•j - 32•i)
F = -1.602 × 10^-19 × ( -32•i + 16•j)
F = 5.126 × 10^-18 •i - 2.563 × 10^-18 •j
Then, the x component of the force is
Fx = 5.126 × 10^-18 N
Also, the y component of the force is
Fy = -2.563 × 10^-18 N
Answer
given,
length of bar = 80 cm
mass of the bar = 10 kg
smaller mass = 4 kg
distance = 20 cm
taking moment about B
difference between two scale = 8 - 6
= 2 N
Answer: My initial velocity is 5 m/s.
Explanation:
In this case, momentum can be conserved.
initial momentum = final momentum
Since both the bodies come to rest after collision,
Final momentum = 0
Let my velocity be v, and mass, m1 = 60 kg
Friend's mass, m2 = 100 kg
Friend's velocity, v2 = 3 m/s
Intial momentum = m1v + m2v2
= 60v + 300
Conserving momentum,
60v + 300 = 0
v= -5 m/s
( Negative sign indicates that me and my friend are moving in opposite directions that is towards each other)
