5) Choose the best revision of the following statement: "All the isotopes of a particular element decay radioactively by
emitting electrons."
A. All the isotopes of a particular element are stable and do not decay.
B. Some isotopes are stable and others are unstable. Unstable isotopes decay by emitting various subatomic
particles and radiation
C. Some isotopes are stable and others are unstable. Unstable isotopes decay by emitting protons or
electrons.
D. The statement is correct as it is currently written.

Answer:

(a) You can tell that have the same strength because they have attracted the same amount of paper clips.

(b) Iron is used in electromagnets because steel retained magnetic properties after the power was turned off, but in the iron, the paper clips dropped off right away.

Answer:

104653.13J

Explanation:

Given parameters:

Mass of roller coaster  = 625kg

Speed  = 18.3m/s

Unknown:

Kinetic energy  = ?

Solution:

The kinetic energy is the energy due to the motion of a body.

     Kinetic energy  = [tex]\frac{1}{2}[/tex] x m x v²  

m is the mass

v is the speed

    Kinetic energy  =  [tex]\frac{1}{2}[/tex]  x 625  x  18.3²   = 104653.13J

Answer:

  T₀ = 2π [tex]\sqrt{\frac{m}{k} }[/tex]           T = [tex]\sqrt{\frac{5}{6} }[/tex] T₀

Explanation:

When the block is oscillating it forms a simple harmonic motion, which in the case of a spring and a mass has an angular velocity

        w = [tex]\sqrt{k/m}[/tex]

To apply this formula to our case, let's look for the equivalent constant of the springs.

Let's start with the springs in parallels.

* the three springs in the upper part, when stretched, lengthen the same distance, therefore the total force is

       F_total = F₁ + F₂ + F₃

the springs fulfill Hooke's law and indicate that the spring constant is the same for all three,

       F_total = - k x - k x - kx = -3k x

therefore the equivalent constant for the combination of the springs at the top is

      k₁ = 3 k

* the two springs at the bottom

following the same reasoning the force at the bottom is

        F_total2 = - 2 k x

the equivalent constant at the bottom is

         k₂ = 2 k

now let's work the two springs are equivalent that are in series

the top spring is stretched by an amount x₁ and the bottom spring is stretched x₂

            x₂ = x -x₁

            x₂ + x₁ = x

if we consider that the springs have no masses we can use Hooke's law

            [tex]-\frac{F_{1} }{k_{1} } - \frac{F_{2}}{k_{2} } = \frac{F}{k_{eq} }[/tex]

therefore the equivalent constant is the series combination is

             [tex]\frac{1}{k_{eq} } = \frac{1}{k_{1} } + \frac{1}{k_{2} }[/tex]

we substitute the values

             \frac{1}{k_{eq} }  = \frac{1}{3k } + \frac{1}{2k }  

             \frac{1}{k_{eq} }  = \frac{5}{6k} }  

              k_eq = [tex]\frac{6k}{5}[/tex]  

therefore the angular velocity is

             w = [tex]\sqrt{\frac{6k}{5m} }[/tex]  

angular velocity, frequency, and period are related

           w = 2π f = 2π / T

           T = 2π / w

            T = 2π [tex]\sqrt{\frac{5m}{6k} }[/tex]

           T₀ = 2π [tex]\sqrt{\frac{m}{k} }[/tex]

           T = [tex]\sqrt{\frac{5}{6} }[/tex] T₀

Answer:

F=84.0 Hz

Explanation:

Using the equation f= n (v/2L),  frequency equals number of loops times velocity over 2 times the length, in order to get 60.0 Hz of frequency from 5 loops, v/2L would have to equal 12. (12*5=60) v/2L is constant, so to find the frequency of 7 loops you would times 7 by 12 to get 84.0.

Hope this helped! :)