Answer: 75 ft
Explanation:
Breaking distance = Speed²/ 20
= 30²/20
= 45 feet
Stopping distance = Speed + braking distance
= 30 + 45
= 75 ft
The correct choice is D .
This is called a<em> standing wave</em> since the waves don't move ALONG the rope. They just kind of stand in one place on the rope. if you just whip a long rope that's not tied to anything, you see the wave move along the rope, this is a TRANSVERSE wave. When you crack a qhip you send a transverse wave down the whip which concentrates in the tip, accelerating the tip to faster than the speed of sound resulting in a tiny sonic boom or "whip crack".
The correct answer is:
<span>Point charges must be in a vacuum.
In fact, the usual form for of the Coulomb's law is:
</span>

<span>where
</span>

is the permittivity of free space
<span>q1 and q2 are the two charges
q is the separation between the two charges
However, this formula is valid only if the charges are in vacuum. If they are in a material medium, the law is modified as follows:
</span>

where

is the relative permittivity, which takes into account the dielectric effects of the material.
Hello,
<span>A police car parked on the side of the highway emits a 1200 Hz sound that bounces off a vehicle farther down the highway and returns with a frequency of 1250 Hz.
How fast is the vehicle going?
Doppler equation formula: </span>ƒL = ƒS(v - vL)/(v - vS)
The wave returns with a frequency of 1250 Hz, the <span>echo frequency is higher; the car must be traveling towards the police car.
</span><span>The wave echo is coming back towards the police car at the same speed as the sound wave travels towards the moving car so t</span><span>he relative speed between the cars is half of the speed of the echo.
* </span><span>speed of sound equals about 337 m/s </span>
2v / 337 = (1250/1200) - 1
<span>2v = 14.04 m/s </span>
<span>v = 7.02 m/s
</span>
Thus, the vehicle is going 7.02 m/s.
Faith xoxo