Answer: His average speed in mph over the last 400 m is 7.7 m/s.
Explanation:
Given: Hicham El Guerrouj of Morocco holds the world record in the 1500 m running race. He ran the final 400 m in a time of 51.9 s.
We know that , speed = 
Here , distance = 400m and time = 51.9 s
Then, speed = 
Hence, his average speed in mph over the last 400 m is 7.7 m/s.
A certain amount of Conductivity
Answer:
a.Insulators can be used to increase the amount of current that can flow through a resistor without increasing its temperature.
Explanation:
A conductor has low resistance, while an insulator has much higher resistance. Devices called resistors control amounts of resistance into an electrical circuits. Electric charges inside an insulator are bound to the individual atoms or molecules, not being able to move inside the material.
When you turn up the resistance, the electric current flowing through the circuit is reduced
Ohm's law:
V = I * R
R = V/I
An Ohmic conductor would have a linear relationship between the current and the voltage. With non-Ohmic conductors, the relationship is not linear. Most metals are good conductors example silver, copper etc.
<span>A light-year is the total distance that light can travel in 1 year.
Since, We know the speed of light (c) in vacuum= 299792458 metres per second
And, there are 365.25 days in an year, or t= (365.25*24*60*60) seconds
Hence a light-year (d)=c*t
=299792458Ă—365.25Ă—24Ă—60Ă—60 metres
=9,460,730,472,580,800 metres
â‰9.46073Ă—10^15 metres</span>
The distance starting from the point to the lighthouse would be regarded as the hypotenuse.
And also will be the radius of the circle the beam of light is generating at that point.
So get the radius first
r = sqrt (1^2 + 5^2)
r = 5.099 km
find the circumference:
C = 2*pi * 5.099 km
C = 2 * 16.01898094
C = 32.04 km
Then find the speed in km/sec
One revolution: 60/2 = 30 sec per revolution
Speed = 32.04 km/30 sec
S = 1.068 km/sec is the speed of light
