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shepuryov [24]
3 years ago
15

A 3.00 kg object is fastened to a light spring, with the intervening cord passing over a pulley. The pulley is frictionless, and

its inertia may be neglected. The object is released from rest when the spring is unstretched. If the object drops 10.0 cm before stopping, find (a) the spring constant of the spring and (b) the speed of the object when it is 5.00 cm below its starting point.
Physics
1 answer:
finlep [7]3 years ago
3 0

Answer:

Part a)

k = 588.6 N/m

Part b)

v = 0.7 m/s

Explanation:

As we know that initially block is at rest

now if block is released from rest then it will go down by 10 cm and again comes to rest

so here we have

Part a)

Work done by gravity + work done by spring force = change in kinetic energy

W_g + W_{spring} = 0 - 0

mg(0.10) + \frac{1}{2}k(0^2 - 0.10^2) = 0

3(9.81)(0.10) - \frac{1}{2}k(0.10)^2 = 0

k = 588.6 N/m

Part b)

Now when spring is stretch by x = 5 cm then the speed of the block is given as

mgx' + \frac{1}{2}k(0^2 - x'^2) = \frac{1}{2}mv^2 - 0

here we have

x' = 0.05 m

3(9.81)(0.05) - \frac{1}{2}(588.6)(0 - 0.05^2) = \frac{1}{2}(3) v^2

1.4715 - 0.736 = 1.5 v^2

v = 0.7 m/s

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Harry is a professional astronomer. The pictures below show two types of telescopes Harry owns.
Dafna1 [17]
The best answer is
C) reflecting telescope, because it can be made large enough to gather more radiations (or light) from distant objects. 

Reflecting telescopes, unlike refracting telescopes, can be made larger and larger to collect more light, with more precision, from larger distances. Refracting telescopes generally are not used for any demanding purposes, such viewing objects in space by professional astronomers. 
4 0
3 years ago
The second ionization energy is the energy required to remove the _______ Electron after a __________ one has been removed.
Sindrei [870]

The second ionization energy is the energy required to remove the <u>second </u>electron after a <u>valence</u> one has been removed.

<h3><u>Explanation:</u></h3>

For an element, the first ionization energy is defined as the amount of energy required to remove one electron from the outermost valence shell of a neutral atom. Removing one electron increases the number of protons, making it a 1+ ion.  

The nucleus (protons) has more bonding to the electrons with negative charge and thus more energy is required if another electron needs to be removed. This higher energy required to remove second electron from a 1+ ion (after the first one has been removed) is termed as the second ionization energy. Second ionization energy leads to formation of a 2+ ion. Similarly, third ionization energy is higher than second ionization energy.

6 0
3 years ago
A student sits on a rotating stool holding two 3.09-kg masses. When his arms are extended horizontally, the masses are 1.08 m fr
schepotkina [342]

Answer:

a

The New angular speed is  w_f = 2.034 rad/s

b

The Kinetic energy before the masses are pulled in is  KE_i = 3.101 \ J

c

The Kinetic energy after the masses are pulled in is   KE_f = 8.192 \ J

Explanation:

From the we are told that masses are 1.08 m from the axis of rotation, this means that

             The radius r =1.08m

              The  mass is m = 3.09\  kg

              The  angular speed w = 0.770 \ rad/sec

  The moment of inertia of the system excluding the two mass I = 3.25 \ kg \cdot m^2

           New radius  r_{new} = 0.34m

             

Generally the conservation of angular momentum can be mathematical represented as

                         w_f = [\frac{I_i}{I_f} ]w_i .....(1)

Where w_f is the final angular speed

           w_i is the initial  angular speed

          I_i is the initial moment of inertia

           I_f is the final moment of inertia

Moment of inertia is mathematically represented as

                       I = m r^2

Where I is the moment of inertia

          m is the mass

           r is the radius

So the Initial moment of inertia is given as  

     I_i = moment \ of \  inertia \ of\  the  \ two \  mass \ + 3.25 \ kg \cdot m^2

     I_i = 2m r^2 + 3.25

The multiplication by is because we are considering two masses

    I_i = 2 [(3.09)(1.08)^2] +3.25 = 10.46 kg \cdot m^2

So the final  moment of inertia is given as  

     I_f = 2[(3.09)(0.34)^2] +3.25 = 3.96 \ kg \cdot m^2      

Substituting these values into equation 1

         w_f = [\frac{10.46}{3.96} ] * 0.77 = 2.034 \ rad/sec                                                          

Generally Kinetic energy is mathematically represented in term of moment of inertia as

                       KE = \frac{1}{2} * I * w^2

Now considering the kinetic energy before the masses are pulled in,

                     KE_i = \frac{1}{2} * I_i * w^2_i

The Moment of inertia would be  I_i = 10.46 \ Kg \cdot m^2

  The Angular speed would be  w_i = 0.77 \ rad/s

Now substituting these value into the equation above

              KE_i = \frac{1}{2} * (10.46) * (0.770)^2 = 3.101 J

Now considering the kinetic energy after the masses are pulled in,                      

               KE_f = \frac{1}{2} * I_f * w^2_f

The Moment of inertia would be  I_f = 3.96 \ Kg \cdot m^2

The Angular speed would be  w_f = 2.034 \ rad/s

Now substituting these value into the equation above

                        KE_f= \frac{1}{2} *(3.96)(2.034)^2  

                        = 8.192J        

8 0
3 years ago
In the image, the net force is _______.
Sveta_85 [38]

Your correct answer would be 0 N

The forces are pulling in opposite directions, therefore they cancel each other out.

Hope that helps!!

:)

4 0
3 years ago
An experiment is designed to compare the differences in learning outcomes
MissTica

Answer:

B. Randomly assigning students to the two different groups

Explanation:

The bias can be controlled by making use of the randomized block design where we divide the subject into subgroups also called blocks and randomly assign treatment conditions to each block.

In this case, the blocks or sub groups are learning math from a video game and learning it from traditional classroom activities.

So the best way to control the bias is by randomly assigning students to the different groups.

6 0
2 years ago
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