Answer :
The magnet produces a domain alignment that allows the iron become magnetic such that it is attracted to the original magnet.the magnetic iron can then create the same effect on another piece of iron.
Explanation:
the piece of magnet is brought closer to the iron where the domains of the iron align including the magnetic poles.
Answer:
Normal force=mg
Explanation:
The reaction force of weight is the normal force.
in order to find the normal for we need to write all the forces and set it equal to the net force:
N-mg=ma (since it is a constant speed the a=0)
N=mg
Answer:
Therefore,
The frequency heard by the engineer on train 1
Explanation:
Given:
Two trains on separate tracks move toward each other
For Train 1 Velocity of the observer,
For Train 2 Velocity of the Source,
Frequency of Source,
To Find:
Frequency of Observer,
(frequency heard by the engineer on train 1)
Solution:
Here we can use the Doppler effect equation to calculate both the velocity of the source 
and observer 
, the original frequency of the sound waves 
and the observed frequency of the sound waves 
,
The Equation is
Where,
v = velocity of sound in air = 343 m/s
Substituting the values we get
Therefore,
The frequency heard by the engineer on train 1
Answer:
Option A is the correct answer.
Explanation:
The instantaneous acceleration = Change in velocity in velocity/Time taken
The slope of the graph should give instantaneous acceleration.
Slope of a graph = Change in value of Y -axis / Change in values of X -axis
Comparing both the equations
Change in value of Y -axis = Change in velocity in velocity
Change in values of X -axis = Time taken
So velocity values should be on the Y axis and Time values should be on the X axis.
Option A is the correct answer.
