They are repelled from the negative end and attracted to the positive end because of its negative charge. Remember, opposites attract and like charged repel
(a) The frequency observed by the passenger on the east-bound train when they are 1000 m apart is 675.5 Hz.
(b) After 10 seconds, the frequency observed by the passenger on the east-bound train will be greater than the frequency observed when they are 1000 m apart.
<h3>Observed frequency</h3>
The frequency observed by the passenger on east-bound train is calculated by applying Doppler shift formula.

where;
- f is observed frequency
- f₀ is original frequency or source frequency
- v is speed of sound
- v₀ is speed of observer (positive when moving towards source)
- vs is source frequency (negative when moving towards observer)
<h3>when the two trains are 1000 m apart</h3>

The frequency observed by the passenger increases with decrease in distance between the two trains.
Thus, after 10 seconds, the frequency observed by the passenger on the east-bound train will be greater than the frequency observed when they are 1000 m apart.
Learn more about Doppler shift here: brainly.com/question/23841569
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Answer:
The statements are missing!
The correct answer to the question is C i.e C represents the friction from air resistance.
EXPLANATION:
Before coming into any conclusion, first we have to understand friction.
The friction is the opposing force which acts tangentially between two bodies in contact when there is a relative motion between them.
The air resistance is that frictional force which is provided by the air to the moving body through it. Hence, the friction from air resistance will be directed opposite to the motion of the body.
In the given diagram, the airplane is going horizontally. The force A acts in forward direction while force C acts in backward direction. The forces B and D are acting vertically. There is no motion in vertical direction. Hence, the net force of A and C will cause the airplane to move.
As the plane is moving along the direction of A, the frictional force must act along the direction of C.
<u>Answer</u>
3 Ohms
<u>Explanation</u>
when the resistors are in series, the resistance in the circuit increases. For example, if two resistors, R1 and R2 are in series, the combined resistance is R1+R2.
When connected in parallel, the total resistance is the reciprocal of (1/R1 + 1/R2)
In this case the resistors are in parallel.
Total resistance = (1/12 + 1/4)⁻¹
= (1/3)⁻¹
= 3 Ohms