The correct choice is
D. 22 Hz and 42 Hz.
In fact, the beat frequency is given by the difference between the frequencies of the two waves:

In this problem, the beat frequency is
, therefore the only pair of frequencies that gives a difference equal to 20 Hz is
D. 22 Hz and 42 Hz.
Answer:
d = 90 ft
Explanation:
Here in each swing the distance sweeps by the swing is half of the initial distance that it will move
So here we can say that total distance in whole motion is given as

since it is half of the distance that it will move in each swing so it would be a geometric progression with common ratio of 1/2
so sum of such GP is given by the formula



Answer:
Balanced forces: When a number of forces acting on a body do not cause any change in its state of rest or of uniform motion along a straight line then the forces are said to be balanced forces. In other words, a body is said to be underbalanced forced when the resulting force acting on the body is zero.
The balanced forces:
⋅ Cannot set any stationary body into motion.
⋅ May change the shape and size of soft objects.
⋅ Cannot change the speed/velocity of a moving body.
Unbalanced forces:
When the resultant of all the forces acting on a body is not zero, then forces are called unbalanced forces.
Example:
⋅ Game of tug of war: When the forces exerted by both the teams are equal, then the rope does not move. But, if the force applied by team A is greater than team B, then the rope, as well as members of the weaker team, i.e., B, will be pulled towards A. The unbalanced force can (a) Set a stationary body in motion.
⋅ Set a moving body at rest.
⋅ Change the direction of motion.
Explanation:
give me an one thanks please
Answer:
<h2>I don't know the answer but I have explanation </h2>
Explanation:
<h3>Science is further treated in a number of articles. For the history of Western and Eastern science, see science, history of. For the conceptualization of science and its interrelationships with culture, see science, philosophy of. For the basic aspects of the scientific approach, see physical science, principles of; and scientific method.Science can be divided into different branches based on the subject of study. The physical sciences study the inorganic world and comprise the fields of astronomy, physics, chemistry, and the Earth sciences. The biological sciences such as biology and medicine study the organic world of life and its processes. Social sciences like anthropology and economics study the social and cultural aspects of human behaviour.Science, any system of knowledge that is concerned with the physical world and its phenomena and that entails unbiased observations and systematic experimentation. In general, a science involves a pursuit of knowledge covering general truths or the operations of fundamental laws.</h3>