Answer:
7500 m
Explanation:
The radar emits an electromagnetic wave that travels towards the object and then it is reflected back to the radar.
We can call L the distance between the radar and the object; this means that the electromagnetic wave travels twice this distance, so
d = 2L
In a time of

Electromagnetic waves travel in a vacuum at the speed of light, which is equal to

Since the electromagnetic wave travels with constant speed, we can use the equation for uniform motion ,so:
(1)
where


, where L is the distance between the radar and the object
Re-arranging eq(1) and substituting, we find L:

Answer:
Friction force is independent of the direction of the contacting surfaces
Explanation:
It can go any way depending on how much force is being out on it.
Answer:
The speed of the laser light in the cable, 
Explanation:
It is given that,
Wavelength of Argon laser, 
Refractive index, n = 1.46
Let
is the speed of the laser light in the cable. The speed of light in a medium is given by :



or

So, the speed of the laser light is
. Hence, this is the required solution.
Answer:
200 C
Explanation:
Let C1 and C2 be their charges. According to Coulomb's law

where k =
is the constant, R = 0.4m is the distance between them, F = 120 N is their resulting charge force


Since their total charge is 200C:
or 
We can substitute the above equation


or
So the larger charge is C = 200 C