Answer:
t=1.623 sec
Explanation:
The distance traveled before the echo is had is:

Given the speed of sound as v=345m/s, we use the speed equation to solve for t:

Hence, it takes 1.623 seconds to hear the echo.
Answer:
The sphere C carries no net charge.
Explanation:
- When brougth close to the charged sphere A, as charges can move freely in a conductor, a charge equal and opposite to the one on the sphere A, appears on the sphere B surface facing to the sphere A.
- As sphere B must remain neutral (due to the principle of conservation of charge) an equal charge, but of opposite sign, goes to the surface also, on the opposite part of the sphere.
- If sphere A is removed, a charge movement happens in the sphere B, in such a way, that no net charge remains on the surface.
- If in such state, if the sphere B (assumed again uncharged completely, without any local charges on the surface), is touched by an initially uncharged sphere C, due to the conservation of charge principle, no net charge can be built on sphere C.
Answer:
The resonant frequency of this circuit is 1190.91 Hz.
Explanation:
Given that,
Inductance, 
Resistance, R = 150 ohms
Capacitance, 
At resonance, the capacitive reactance is equal to the inductive reactance such that,

f is the resonant frequency of this circuit



So, the resonant frequency of this circuit is 1190.91 Hz. Hence, this is the required solution.
Answer: The correct answer for the blank is- a. change its position relative to other objects.
Perception of motion can be described as a phenomenon of inferring the direction and speed and of objects, which are moving in a visual scene.
An object is said to be in motion if its position is changed with respect to objects that are present in its surrounding.
Thus, in order to sense motion of objects, humans beings are required to see an object change its position with respect to other objects.