Answer:
(a) 89 m/s
(b) 11000 N
Explanation:
Note that answers are given to 2 significant figures which is what we have in the values in the question.
(a) Speed is given by the ratio of distance to time. In the question, the time given was the time it took the pulse to travel the length of the cable twice. Thus, the distance travelled is twice the length of the cable.
(b) The tension, 
, is given by
where 
is the speed, is the tension and 
is the mass per unit length.
Hence,
To determine , we need to know the mass of the cable. We use the density formula:
where 
is the mass and 
is the volume.
If the length is denoted by 
, then
The density of steel = 8050 kg/m3
The cable is approximately a cylinder with diameter 1.5 cm and length or height of 620 m. Its volume is
We will apply the concept of period in a pendulum, defined as the product between 2
by the square root of the length over gravity, this is mathematically
Here,
T = Period
L = Length
g = Acceleration due to gravity
For the period to be 1 second, then we must look for the necessary length for such a requirement so
The meter's length would be slight less than one-fourth of its current length. Also, the number of significant digits depends only on how precisely we know g, because the time has been defined to be exactly 1s.
Therefore the correct answer is C.
Answer: c
Explanation: because if it increases then it gets hotter
if it decreases then its getting colder.
The superscripts in a chemical formula are the overall charge of an ion
D.Radiant energy does not require a medium through which to travel.
