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28 Common Questions of a Simple Alternating Current Circuit,- Learning ac current circuit in 28 common questions of a single ac current circuit problem. This topic discussed at grade 12 high school.


Given an ac circuit contents a resistor (R), an inductor (L) and a capacitor (C) in series combination with voltage source of V = 120 sin (125t) volt.


  • a) angular frequency of the ac source
  • b) frequency of the ac source
  • c) period of ac source
  • d) voltage amplitude of ac source
  • e) effective voltage of ac source
  • f) peak to peak voltage of ac source
  • g) inductive reactance of the inductor
  • h) capacitive reactance of the capacitor
  • i) circuit impedance
  • j) amplitude of circuit current
  • k) root-mean-square current of circuit
  • l) voltage across d-e
  • m) voltageacross e-f
  • n) voltage across f-g
  • o) voltage across d-f
  • p) voltage across e-g
  • q) voltage across d-g
  • r) circuit power factor
  • s) phase angle
  • t) power dissipated in the circuit
  • u) Circuit properties whether resistive, inductive or capacitive
  • v) instantaneous value of voltage when t = (π/150) sec
  • w) current equation of ac source
  • x) instantaneous value of current of ac source when t = (0,016 π)
  • y) average voltage
  • z) current average
  • aa) current and voltage in phasor
  • bb) resistance, inductive reactance and capacitive reactance in phasor


5 Common Problems of Torques and Moments of Inertia 5 common problems of torques and moments of inertia. Finding the torques caused of forces and moments of inertia of various bodies. This topic are learned at grade 11 high school level.

Question 1
Given 4 forces:
F1 = 100 N
F2 = 50 N
F3 = 25 N
F4 = 10 N
acting on a body with point P as its rotation axis. See the figure below

ABCD is a square with 4 m of length for each side, use tan 53o = 4/3, find the magnitude of the torque of these forces about point P and its direction!


8 Common Questions of Vectors 8 common problem of vectors, finding the vectors resultant with some different methods.
Problem 1
Given two vectors with magnitudes both of them are 10 Newton.

The angle between two vectors is 60°, find the resultant!

5 Common Problems of Works Learning works and forces in 5 common problems. The work done by forces, the difference of kinetics energy and the difference of potential energy will be covered in this short discussion.

Problem 1
A force F of 120 N acts on a block with an angle of 37o , see the below figure.

If the block displacement is 10 m, find the work done by the force!


3 Types of Common Problems in Projectile Motion These are three types of the most common problems questions of projectile motion. Normal parabolic, a half parabolic and fully parabolic type.



1) Given a figure of a moving particle in projectile trajectory as shown below:

The initial velocity of particle is 100 m/s with elevation angle of 37o . Use the acceleration due to gravity 10 m/s2, sin 37o = 3/5 and cos 37o = 4/5
a) initial vector component on x axis
b) initial vector component on y axis
c) particle velocity for t = 1 sec
d) the direction of velocity for t = 1 sec
e) the height reached by particle for t = 1 sec
f) the horizontal distance reached for t = 1 sec
g) the time needed to reach the highest point
h) particle velocity at the highest point
i) the maximum height reached ( Ymaks )
j) the time needed to reach the maximum horizontal range
k) the maximum range reached ( Xmaks )



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