Answer:

Explanation:
Using the Gauss Law, we obtain the electric Field for a uniform large line of charge:


We calculate the potential difference from the electric field:

Answer: B
Explanation:
The friction force is less than the tension force
Answer:
<em>a) 28877 AU</em>
<em>b) 1.795 sec</em>
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Explanation:
Time it took the radio signal to reach earth = 4 hours = 4 x 3600 = 14400 s
speed of radio signal = speed of vacuum speed of light = 3 x 10^8 m/s
Distance traveled by this signal = speed x time
distance = 3 x 10^8 x 14400 = 4.32 x 10^12 m
One Astronomic unit AU is the distance between the Earth and the sun and it is approximately equal to 1.496 x 10^8 m
The distance traveled by the signal in AU = (4.32 x 10^12)/(1.496 x 10^8) = <em>28877 AU</em>
b) The minimum separation between Earth and Mars = 0.36 AU
This distance = 0.36 x 1.496 x 10^8 = 538560000 m
Time that will be taken for a radio signal to travel this distance = distance/speed
==> 538560000/(3 x 10^8) = <em>1.795 sec</em>
Frequency= velocity of light/wave length
Fr= 3×10^8/510×10^-9
Frequwency=5.88×10^14 Hz
Answer:
The elevator must be moving upward.
Explanation:
During the motion of an elevator, the weight of the person deviates from his or her actual weight. This temporary weight during the motion is referred to as "Apparent Weight". So, when the elevator is moving downward, the apparent weight of the person becomes less than his or her actual weight.
On the other hand, for the upward motion of the elevator, the apparent weight of the person becomes more than the actual weight of that person.
Since the apparent weight (645 N) of the student, in this case, is greater than the actual weight (615 N) of the student.
<u>Therefore, the elevator must be moving upward.</u>