Answer:
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Explanation:
The gravitational force of the earth keeps us bound to the earth. Gravitational force between earth and sun makes the earth move around the sun. Gravitational force between moon and earth makes the moon go around the earth.
i am 2.5 with the thhe 2020 is 3 and 5 is 7
The statement which describes how a machine can help make work easier is that It can put out more force than the input force by decreasing the distance over which force is applied, therefore the correct option is option A.
<h3>What is work done?</h3>
The total amount of energy transferred when a force is applied to move an object through some distance
The work done is the multiplication of applied force with displacement.
Work Done = Force * Displacement
As work done depends both on the force as well as the displacement force and be reduced by reducing the displacement if the same amount of work is performed by the machine.
The correct answer is option A since the statement that describes how a machine might assist in making work easier says that it can put out greater force than the input force by reducing the distance over which force is exerted.
Learn more about work done from here
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Answer:
Option C
Explanation:
Given:
- Depth of tissue d = 12 cm
- frequency of ultrasound f = 1 MHz
- Input Intensity I_i = 1000 W/m^2
- attenuation coefficient soft tissue a = 0.54
Find:
- Out-put intensity at the required depth
Solution
- The amount of attenuation in (dB) with the progression of depth is given by:
Attenuation = a*f*d
Attenuation = 0.54*12*1
Attenuation = 6.48 dB
- The relation with attenuation and ratio of input and output intensity is given by:
Attenuation = 10*log_10 (I_i / I_o)
6.48 dB = 10*log_10 (I_i / I_o)
I_i / I_o = 10^(0.648)
I_o = 1000 / 10^(0.648)
I_o = 225 W/m^2
- Hence the answer is option C: I_o = 250 W/m^2
The force between two system is inversely proportional to the square the distance between them. The indirect proportion between these items may be expressed as,
F = k / d²
where k is the constant proportionality. Substituting the known values,
0.68 N = k / (1 m)² ; k = 0.68
For the second case,
F = 0.68 / (0.5 m)² = 2.72 N
Thus, the answer is 2.72 N.
