Answer:
21/5 seconds or 4.2 seconds
Explanation:
Distance=Speed*Time
21=5 *Time
21/5=Time
4.2=time
Two analogies:
1. The wires are like hoses full of water. As soon as you turn on the water, water is pushed out the end of the hose.
2. Although the electrons only move at 1mm/s, the electomagnetic pulse travels through the circuit at near speed of light (varies btw .1c to .9c). It is this pulse that provides the pressure to push the electrons out the end of the wire into the light
Answer:
(a) Yes, it is possible by raising the object to a greater height without acceleration.
Explanation:
The work-energy theorem states that work done on an object is equal to the change in kinetic energy, and change in kinetic energy requires a change in velocity.
If kinetic energy will not change, then velocity will not change, this means that there will be constant velocity and an object with a constant velocity is not accelerating.
If the object is not accelerating (without acceleration) and it remains at the same height (change in height = 0, and mgh = 0).
Thus, for work to be done on the object, without changing the kinetic energy of the object, the object must be raised to a greater height without acceleration.
Correct option is " (a) Yes, it is possible by raising the object to a greater height without acceleration".
Answer:
4847.94844926 kg/m³
Explanation:
= Actual density of cube = 1900 kg/m³
= Density change due to motion
v = Velocity of cube = 0.92c
c = Speed of light = 
Relativistic density is given by

The cube's density as measured by an experimenter in the laboratory is 4847.94844926 kg/m³