The answer is 20km because you go to yours friend's house and back then an extra 10km. 5+5+10=20km
They’re right that is the answer
Answer: Microwaves
Explanation:
RADAR stands for radio detection and ranging. Radio waves range from 300 GHz to 30 Hz. Modern radar uses higher frequency of waves for detection. These waves are microwaves (300 MHz-300 GHz). Microwaves are types of radio waves and are used in the radar detection.
The electromagnetic wave which has highest frequency is gamma wave but it is not used for radar detection.
Hence, the correct answer is microwaves are the type pf radio waves which have the highest frequency and are used in radar detection.
1) Acceleration of the sled
The acceleration of the sled is given by the net force acting in the direction parallel to the incline. There are two forces acting along this direction: the component of the weight parallel to the ramp (downward) and the friction (upward). Therefore, the net force acting in this direction is
![F=mg sin \theta- F_f =(8 kg)(9.8 m/s^2)(sin 50^{\circ})-2.4 N=57.7 N](https://tex.z-dn.net/?f=F%3Dmg%20sin%20%5Ctheta-%20F_f%20%3D%288%20kg%29%289.8%20m%2Fs%5E2%29%28sin%2050%5E%7B%5Ccirc%7D%29-2.4%20N%3D57.7%20N)
And the acceleration is given by Newton's second law:
![a=\frac{F}{m}=\frac{57.7 N}{8 kg}=7.21 m/s^2](https://tex.z-dn.net/?f=a%3D%5Cfrac%7BF%7D%7Bm%7D%3D%5Cfrac%7B57.7%20N%7D%7B8%20kg%7D%3D7.21%20m%2Fs%5E2)
2) Normal force
The normal force acting on the sled is equal to the component of the weight perpendicular to the incline, therefore:
![N=mg cos \theta=(8 kg)(9.8 m/s^2 )(cos 50^{\circ})=50.4 N](https://tex.z-dn.net/?f=N%3Dmg%20cos%20%5Ctheta%3D%288%20kg%29%289.8%20m%2Fs%5E2%20%29%28cos%2050%5E%7B%5Ccirc%7D%29%3D50.4%20N)