Answer:

Given:
Mass (m) = 3.0 kg
Uniform speed (v) = 20 m/s
Length of string (r) = 40 cm = 0.4 m
To Find:
Tension in the string (T)
Explanation:
Tension (T) is the string will be equal to centripetal force (
).

Substituting value of m, v & r in the equation:


Tension in the string (T) = 3 kN
Answer:
To balance an equation such as Mg + O2 → MgO, the number of the atoms in the product must equal the number of the atoms in the reactant. Mg + O2 --> MgO. To balance an equation, we CAN change coefficients, but NOT SUBSCRIPTS to balance equations.
Explanation:
Answer:
It is easier to scale the voltage of AC from high to low and low to high than with DC
Explanation:
typically power is used far away from the place where it's generated so to ensure that transmission losses( copper losses) are minimized voltage has to be stepped up during transmission..but due to the fact that most house hold equipment requires low voltage levels it has to be stepped down once it reaches a household/ domestic load...it's easier to do this for Ac than for DC.
Answer:
M' = μ₀n₁n₂πr₂²
Explanation:
Since r₂ < r₁ the mutual inductance M = N₂Ф₂₁/i₁ where N₂ = number of turns of solenoid 2 = n₂l where n₂ = number of turns per unit length of solenoid 2 and l = length of solenoid, Ф₂₁ = flux in solenoid 2 due to magnetic field in solenoid 1 = B₁A₂ where B₁ = magnetic field due to solenoid 1 = μ₀n₁i₁ where μ₀ = permeability of free space, n₁ = number of turns per unit length of solenoid 1 and i₁ = current in solenoid 1. A₂ = area of solenoid 2 = πr₂² where r₂ = radius of solenoid 2.
So, M = N₂Ф₂₁/i₁
substituting the values of the variables into the equation, we have
M = N₂Ф₂₁/i₁
M = N₂B₁A₂/i₁
M = n₂lμ₀n₁i₁πr₂²/i₁
M = lμ₀n₁n₂πr₂²
So, the mutual inductance per unit length is M' = M/l = μ₀n₁n₂πr₂²
M' = μ₀n₁n₂πr₂²