Which is an important step in how an electric motor uses magnetic force to produce motion?
2 answers:
Answer:
B) As the north pole of the electromagnet nears the south pole of the permanent magnet, the current reverses and the poles of the magnets then repel.
Explanation:
As we know that electric motor is based on the concept of torque due to magnetic field on current carrying coil.
Here as the current is passing through the coil the torque on the coil is given as
so here the magnetic field due to coil will continuously repelling the current carrying coil as it will move between the magnetic field so direction of current in the coil will change continuously so that it will always repel by the magnetic field and continuously rotated between the magnets
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Answer:
N₂=20.05 rpm
Explanation:
Given that
R= 19 cm
I=0.13 kg.m²
N₁ = 24.2 rpm
ω₁= 2.5 rad/s
m= 173 g = 0.173 kg
v=1.2 m
Initial angular momentum L₁
L₁ = Iω₁ - m v r ( negative sign because bird coming opposite to motion of the wire motion)
Final linear momentum L₂
L₂= I₂ ω₂
I₂ = I + m r²
The is no any external torque that is why angular momentum will be conserve
L₁ = L₂
Iω₁ - m v r = I₂ ω₂
Iω₁ - m v r = ( I + m r²) ω₂
Now by putting the all values
Iω₁ - m v r = ( I + m r²) ω₂
0.13 x 2.5 - 0.173 x 1.2 x 0.19 = ( 0.13 + 0.173 x 0.19²) ω₂
0.325 - 0.0394 = 0.136 ω₂
ω₂ = 2.1 rad/s
N₂=20.05 rpm
Answer:
Explanation:
For free body diagram see attached sheet .
W is weight of steel girder acting at the middle point of its length . T is tension in the cable .
OB = √ ( 12² - 2² )
= 11.83 m .
OC = 11.83 / 2 = 5.915 m
Taking moment of tension T and weight W about point O
W x OC = T x OB
22 x 5.915 = T x 11.83
T = 22 x 5.915 / 11.83
= 11 kN
Considering forces acting in vertical direction and equating forces in opposite direction
T + R = W
R = W - T
= 22 - 11 = 11 KN
So force of grinder on the ground = R
= 11 KN.
