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riadik2000 [5.3K]
3 years ago
7

As a hiker in Glacier National Park, you are looking for a way to keep the bears from getting at your supply of food. You find a

campground that is near an outcropping of ice from one of the glaciers. Part of the ice outcropping forms a 55.5 ° slope up to a vertical cliff. You decide that this is an ideal place to hang your food supply as the cliff is too tall for a bear to reach it. You put all of your food into a burlap sack, tie an unstretchable rope to the sack, and tie another bag full of rocks to the other end of the rope to act as an anchor. You currently have 22.5 kg of food left for the rest of your trip so you put 22.5 kg of rocks in the anchor bag to balance it out. What happens when you lower the food bag over the edge and let go of the anchor bag? The weight of the bags and the rope are negligible. The ice is smooth enough to be considered frictionless.What will be the acceleration of the bags when you let go of the anchor bag?

Physics
1 answer:
Lorico [155]3 years ago
7 0

Answer:

Acceleration of the bags is 0.861 m/s²

Explanation:

Given:

Mass of the rock, m = 22.5 kg = mass of the food

Slope, Θ = 55.5°

Now, from the figure, we have

T - mgsinΘ = ma            ...................(1)

'a' is the acceleration of the mass

where T is the tension

also for the second mass, we have

mg - T = ma

now substituting the value of T from the equation (1) we get

mg - (ma + mgsinΘ) = ma

or

mg(1 - sinΘ) = (m + m)a

or

a = \frac{mg(1 - sin\theta)}{2m}

on substituting the values we get

a = \frac{9.8\times (1 - sin55.5^o)}{2}

or

a = 0.861 m/s²

Hence, the acceleration of the bags is 0.861 m/s²

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Answer:

A)  B = 5.4 10⁻⁵ T, B) the positive side of the bar is to the West

Explanation:

A) For this exercise we must use the expression of Faraday's law for a moving body

            fem = -  \frac{d \phi }{dt}

            fem = - \frac{d (B l y}{dt}= - B l v- d (B l y) / dt = - B lv

            B = - \frac{fem}{l \ v}

we calculate

             B = - 7.9 10⁻⁴ /(0.73 20)

             B = 5.4 10⁻⁵ T

B) to determine which side of the bar is positive, we must use the right hand rule

the thumb points in the direction of the rod movement to the south, the magnetic field points in the horizontal direction and the rod is in the east-west direction.

Therefore the force points in the direction perpendicular to the velocity and the magnetic field is in the east direction; therefore the positive side of the bar is to the West

4 0
3 years ago
The position-time equation for a cheetah chasing an antelope is:
pochemuha

Answer:

x = 1.6 + 1.7 t^2      omitting signs

a) at t = 0     x = 1.6 m

b) V = d x / d t = 3.4 t

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c) A = d^2 x / d t^2 = 3.4     (at t = 0  A = 3.4 m/s^2)

d)  x = 1.6 + 1.7 * (4.4)^2 = 34.5    (position at 4.4 sec = 34.5 m)

4 0
2 years ago
Suppose the rocket in the Example was initially on a circular orbit around Earth with a period of 1.6 days. Hint (a) What is its
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Answer:

a

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b

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Generally angular velocity is mathematically represented as

            w = \frac{2 \pi}{T}

Where T is the period which is given as 1.6 days = 1.6 *24 *60*60 = 138240 sec

       Substituting the value

         w = \frac{2 \pi}{138240}

             = 4.54*10^ {-5} rad /sec

At the point when the rocket is on a circular orbit  

   The gravitational force =  centripetal force and this can be mathematically represented as

              \frac{GMm}{r^2} = mr w^2

Where  G is the universal gravitational constant with a value  G = 6.67*10^{-11}

            M is the mass of the earth with a constant value of M = 5.98*10^{24}kg

            r is the distance between earth and circular orbit where the rocke is found

               Making r the subject

                     r = \sqrt[3]{\frac{GM}{w^2} }

                        = \sqrt[3]{\frac{6.67*10^{-11} * 5.98*10^{24}}{(4.45*10^{-5})^2} }

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The orbital speed is represented mathematically as

                   v=wr

Substituting value

                  v= (5.78*10^7)(4.54*10^{-5})

                     v= 2.6*10^{3} m/s    

The escape velocity is mathematically represented as

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Substituting values

                             = \sqrt{\frac{2(6.67*10^{-11})(5.98*10^{24})}{5.78*10^7} }

                             v_e= 3.72 *10^3 m/s

7 0
3 years ago
The flywheel of a steam engine runs with a constant angular velocity of 140 rev/min. When steam is shut off, the friction of the
ratelena [41]

Answer:

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A) Using first equation of motion, we have;

ω = ω_o + αt

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We are given, ω_o = 140 rev/min ; t = 1.9 hours = 1.9 x 60 seconds = 114 s ; ω = 0 rev/min

Thus,

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C) we want to find tangential component of the velocity with r = 40cm = 0.4m

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Now, formula for tangential acceleration is;

α_t = α x r

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D) we are told that the angular velocity is now 70 rev/min.

Let's convert it to rad/s;

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So, radial angular acceleration is;

α_r = ω²r = 7.33² x 0.4

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α = √((α_t)² + (α_r)²)

α = √((-8.57 x 10^(-4))² + (21.49)²)

α = √461.82

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3 years ago
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Hope this helps you.

6 0
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