use Newton's gravitational law and 2nd law .....
Answer: 80N (choice #4)
Explanation: The force of gravity is proportional to the inverse of the square of the distance. That means, if the distance is cut in half, the square of that is 1/4, and the inverse of that is a factor 4. So the force increases by a factor of 4. Given that the force is 20N, the new force will be 4*20N=80N.
<span>the speed of something in a given direction. so i think none of these</span>
Answer:
Therefore, the revolutions that each tire makes is:

Explanation:
We can use the following equation:
(1)
The angular acceleration is:



and the initial angular velocity is:



Now, using equation (1) we can find the revolutions of the tire.

Therefore, the revolutions that each tire makes is:

I hope it helps you!
Answer:
sound and radio waves are completely different phenomena.
Explanation: