Answer:
a) 482.5N
b) 17.4N
Explanation:
40 rev/min = 40 * 2π / 60 = 4.2 rad/s
3 rev/min = 3 * 2π / 60 = 0.314 rad/s
The centripetal acceleration that the child is subjected to

And their centripetal force is

From here we can plug the number in
(a) 
(b) 
Answer:
Radius of the loop is 0.18 m or 18 cm
Explanation:
Given :
Current flowing through the wire, I = 45 A
Magnetic field at the center of the wire, B = 1.50 x 10⁻⁴ T
Number of turns in circular wire, N = 1
Consider R be the radius of the circular wire.
The magnetic field at the center of the current carrying circular wire is determine by the relation:
Here μ₀ is vacuum permeability constant and its value is 4π x 10⁻⁷ Tm/A.
Substitute the suitable values in the above equation.

R = 0.18 m
Like poles repel and unlike poles attract. Magnetic poles always occur in pairs of north and south—it is not possible to isolate north and south poles.
Answer:
the velocity at point B is 27120.08 km/hr
Explanation:
check the picture attached for explanation
(if you have Q1: Carbon is found in: living animals and plants, oceans, rocks, atmosphere, and fossil fuels)
Q2: Humans are burning carbon and putting it into the atmosphere.
Q3: True
Q4: While carbon dioxide is in the air waiting to be reabsorbed it traps the sun's heat.
(and if you have Q5: In the last 250 years, the amount of carbon in the air has increased by 40 percent.)