Answer:
800 N
Explanation:
By Newton's third law which states that for every action, there is an equal and opposite reaction.
So, as the earth attracts the person towards its center, the person attracts the earth towards itself with the same magnitude of force but in the opposite direction.
Since the person is attracted towards the center of the earth by an 800 N gravitational force, the the earth is attracted toward the person with an 800 N reaction force.
Ans: Beat frequency =
= 4HzExplanation: The beat frequency is equal to the absolute value of the difference in frequency of the two waves. In other words, the number of beats per second is equal to the difference in frequency. It is due to the destructive and constructive interference. <span>According to this interference, sound will be soft or loud.
Hence. the formula is:
</span>Beat frequency =

<span>
Since,
</span>


Therefore,
Beat frequency =

=> Beat frequency =

-i
Answer:
The sound intensity of train is 1000 times greater than that of the library.
Explanation:
We have expression for sound intensity level,

A train whistle has a sound intensity level of 70 dB
We have

A library has a sound intensity level of about 40 dB
We also have

Dividing both equations

The sound intensity of train is 1000 times greater than that of the library.
Answer:
<em>Thus, the object is accelerating to the left</em>
Explanation:
<u>The Net Force</u>
The net force is the result of adding all the forces as vectors acting on a body.

Each vector can be expressed in its rectangular components Fx and Fy, and the sum is the sum of the rectangular components separately.
Second Newton's law gives the relation between the net force and the acceleration of the body:

We can see the acceleration is a vector with the same direction as the net force.
The diagram shows two vertical forces and two horizontal forces.
The vertical forces are acting in opposite directions and with the same magnitude, thus they cancel out, leaving zero net force in the y-axis.
The horizontal forces are opposite and with different magnitudes. Since the force acting to the left (F3) has a greater magnitude than the force acting to the right (F4), there is a net force directed to the left with a magnitude of 60 N - 20 N = 40 N
Thus, the object is accelerating to the left