A textbook of mass 2.09kg rests on a frictionless, horizontal surface. A cord attached to the book passes over a pulley whose diameter is 0.120m , to a hanging book with mass 2.99kg . The system is released from rest, and the books are observed to move a distance 1.30m over a time interval of 0.750s . Part A What is the tension in the part of the cord attached to the textbook? =9.66N.
Part B What is the tension in the part of the cord attached to the book? Take the free fall acceleration to be = 9.80m/s^2 =15.5N.
Part C What is the moment of inertia of the pulley about its rotation axis? Take the free fall acceleration to be = 9.80 m/s^2????


Answer 1


(A) 9.7 N

(B) 15.4 N

 (C) I = 0.0045 kg m^{2}


mass of text book (M1) = 2.09 kg

mass of book (M2) = 2.99 kg

diameter of the pulley (d) = 0.12 m

radius (r) = 0.06 m

distance moved (s) = 1.30 m

time (t) = 0.75 s

acceleration due to gravity (g) = 9.8 m/s^[2}

(a) what is the tension in the part of the cord attached to the text book?

the text book is moving horizontally, so the tension in this case becomes

tension = mass x acceleration

we can get the acceleration from s = ut + 0.5 at^{2}

since the books are initially at rest u = 0

s = 0.5 at^{2}

1.3 = 0.5 x a x 0.75^{2}

a = 4.643 m/s^[2}


tension (T1) = 2.09 x 4.643 = 9.7 N

(b) what is the tension in the part of the cord attached to the book?

   the book is hanging vertically, so the tension in this case becomes

tension = m x ( g - a )

(g-a) is the net acceleration of the first book

tension (T2) = 2.99 x (9.8 - 4.643) = 15.4 N

(c) What is the moment of inertia of the pulley?

    if the books were to move in the direction of the book, it will cause the pulley to rotate clockwise and if they were to move in the direction of the text book on the table the pulley will rotate in an anticlockwise direction. Taking clockwise rotation of the pulley to be negative while anticlockwise to be positive, we can say  ( T2 - T1 )r = I∝

      where ∝ is the angular acceleration of the pulley relative to its radial  

      acceleration, ∝ = \frac{a}{r}

      ( T2 - T1 )r = I\frac{a}{r}

      I = \frac{(T2 - T1)r^{2}}{a}

      I = \frac{(15.5 - 9.7)0.060^{2}}{4.643}

      I = 0.0045 kg m^{2}

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But is the answer A, B, C, or D


I would say a because it just sounds right. I would've helped u if u had a real question question. 


How does the distance from an eye chart affect the number of letters that are recognized on a line



Distance from the eye chart are used to find defect in the in the eye sights of a patient. If one cannot see far off things, that means he is near sighted. So if he goes away from the eye chart and try to see the letters in the chart, he will see blur image of the letters.

           And if one is far sighted he cannot see the near by things. If one comes closer to the chart and tries to read the letters then he will not be able to read those letters because he is far sighted.

Thus, in this way distance from the eye chart affect to recognize the letters present in the eye chart.

Well, if you are nearsighted which means you can't see far, the father you are the more blurry it will be, resulting to you saying the wrong letter. This then shows the doctor that you can't see far away, nearsighted.

A 70.0 kg skydiver falls towards the earth. If the force due to air resistance is 0 N, what is the acceleration of the skydiver?


The gravitational acceleration g = 9.81 m/s²

The system schema goes person


A particle moves in the xy plane with constant acceleration. At time zero, the particle is at x = 6 m, y = 8.5 m, and has velocity ~vo = (9 m/s) ˆı + (−2.5 m/s) ˆ . The acceleration is given by ~a = (4.5 m/s 2 ) ˆı + (3 m/s 2 ) ˆ . What is the x component of velocity after 3.5 s? Answer in units of m/s.



24.75 m/s


Since it's only asking for the component we can use v_final=v_initial+at which then gives v_final=9+3.5*4.5=24.75 m/s


How does Earth’s atmosphere support life? Check all that apply. It filters out oxygen.
It keeps Earth warm.
It filters UV radiation.
It provides a solid shield.
It provides water in the form of rain.



The atmosphere of planet Earth is not just a mixture of different gasses. But, it makes Earth the only planet that supports living life as far as we know till now.


  • The First option is all wrong because atmosphere provides oxygen and other required elements to living life.
  • The second option is correct as the gasses present in the atmosphere provides enough heat to keep the Earth warm.
  • Third option is correct as Ultra violet rays from the Sun are filtered out by the atmosphere and we are kept safe from there damaging effects.
  • Fourth option is also correct as it provides a shield of protection from any sort of hazardous material coming from space or electromagnetic radiation that are dangerous to living life.
  • Fifth option is also correct as it contains the required features to hold water molecules up there in the air as they travel around the globe in the form of clouds and then comes down in the form of rain.


1, 3, 5.


Living organisms, need oxygen to breathe. UV light is needed for plants and Homo Sapiens, (Humans). And about 80% of the earth is surrounded or covered with water, it is essential. Otherwise, the other info doesn't make sense. Hope this helps.


Match the correct term with the definition Question 1 options:

the positive particle in the nucleus of an atom

an atom of an element that has a different number of neutrons that the standard atom of that element

the number of protons an atom has

protons + neutrons in the nucleus of an atom

the neutrally charged element in the nucleus of an atom


Atomic Mass


Atomic Number



i need help pls


-Positive particle in the nucleus is a (proton)

-Question two..(isotope)

-Number of protons that an atom has..(atomic number)

-protons + neutrons in the nucleus..(atomic mass)

-neutrally charged element in the nucleus..(neutron)


A submarine periscope uses two totally reflecting 45-45-90 prisms with total internal reflection on the sides adjacent to the 45 degree angles. Explain why the periscope will no longer work if it springs a leak and the bottom prism is covered with water. Note: The index of refraction for water is 1.33. The index of refraction for glass is 1.52




Periscope uses 45-45-90 prisms with total internal reflection adjacent to 45°.

refractive index of water, n_a = 1.33

refractive index of glass, n_g = 1.52

When the light enters the water, water will act as a lens and when we see the object from the periscope the object shown is farther than the usual distance.


In short-track speed skating, the track has straight sections and semicircles 16 m in diameter. assume that a 64 kg skater goes around the turn at a constant 13 m/s. what is the horizontal force on the skater?


The diameter of the semicircular portion of the track is 16 m.
Therefore its radius is
r = 8 m.

The tangential velocity of the skater is 13 m/s.
Therefore the angular speed is
ω = v/r = (13 m/s)/(8 m) = 1.625 rad/s

The horizontal force on the skater is due to centripetal acceleration of
a = r*ω² = (8 m)*(1.625 rad/s)² = 21.125 m/s².

The force acting on the 64-kg skater is
F = m*a = (64 kg)*(21.125 m/s²) = 1352 N

Answer: 1352 N


The terminals of a 0.70 Vwatch battery are connected by a 80.0-m-long gold wire with a diameter of 0.200 mm What is the current in the wire? Express your answer using three significant figures.




Let's use Ohm's law:





We know the value of the voltage V, so we need to find the value of R in order to find I. Fortunately there is a relation between the resistivity of a conductor and its electrical resistance given by:



Keep in mind that the electrical resistivity of the gold is a known constant which is and the cross sectional area of the conductor is calculated as:

Because we have a wire in this case, so we assume a cylindrical geometry.

Now replacing our data in (2)

Finally, we know R and V, so replacing these values in (1) we will be able to find the current:

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