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Lena [83]
2 years ago
15

A student sits on a pivoted stool while holding a pair of weights. The stool is free to rotate about a vertical axis with neglig

ible friction. The moment of inertia of student, weights, and stool is 5.25 kg.m². The student is set in rotation with arms outstretched, making one complete turn every 2.2 s, arms outstretched. Consider opposite of turning direction as positive.
Quiz 6 Question4
What is the initial angular velocity of the system?

Answer 1
Choose...
As he rotates, he pulls the weights inward so that a new moment of inertia of the system (student, objects, and stool) becomes 4 kg.m2. What is the new angular velocity of the system?


Answer 2
Choose...
Physics
1 answer:
Blababa [14]2 years ago
4 0

Answer:

<u>Please Mark As Brainliest!!</u>

a) 4.99 rad/sec b) 6.24 rad/sec c) 7.03 J

Explanation:

a)  If the student completes one turn in 1.26 sec, this is called the period of the movement.

If we take into account that the angle rotated during one turn is 2π rads, by definition of angular velocity, we can get this value as follows:

ω = Δθ / Δt = 2*π rad / 1.26 seg = 4.99 rad/sec.

b) As no external torques are acting on the system, the total angular momentum must be conserved, so we can write the following equation:

Li = Lf   ⇒  I₁ * ω₁  = I₂* ω₂

So, we can solve for ω₂, as follows:

ω₂ = (I₁ * ω₁) / I₂ = 6.24 rad/sec

c) Appying the work-energy theorem, we know that the work done by the student, must be equal to the change in the kinetic energy, which in this case is only rotational, so we can write:

W = 1/2 I₂* ω₂² - 1/2 I₁ ω₁²

W =1/2 ((2.25 kg.m² * (6.24)²) (rad/sec)² - (1.8 kg.m²* (4.99)²) (rad/sec)²)  

W = 7.03 J

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Answer:

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A baseball has a mass of 0.145 kilograms, and a bowling ball has a mass of 6.8 kilograms. What is the gravitational force betwee
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We can use the equation for Newton's Law of Gravitation
Fg = (Gm₁m₂)/r²
Where gravitational constant = G = 6.674 x 10⁻¹¹ N · m²/kg²
mass m₁ = 0.145 kg
mass m₂ = 6.8 kg
distance between centers of masses = r = 0.5 m

Substitute these values into... 
Fg = (Gm₁m₂)/r²
Fg = ((6.674 x 10⁻¹¹)(0.145)(6.8)) / (0.5)²
Fg = 2.63 x 10⁻¹⁰ N 

Therefore, your answer should be 
<span>2.6 × 10–10</span>
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True or false: The therapeutic alliance is defined as the level of commitment a patient has to therapy.
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A wire 95.0 mm long is bent in a right angle such that the wire starts at the origin and goes in a straight line to x = 40.0 mm
qaws [65]

Answer:

0.1040512455 N

36.03^{\circ}\ or\ 323.97^{\circ}in\ CCW\ direction

0.05925 N

29.74^{\circ}\ or\ 330.26^{\circ}in\ CCW\ direction

Explanation:

I = Current

B = Magnetic field

Separation between end points is

l=\sqrt{40^2+55^2}\\\Rightarrow l=68.00735\ mm

Effective force is given by

F=IlB\\\Rightarrow F=5.1\times 68.00735\times 10^{-3}\times 0.3\\\Rightarrow F=0.1040512455\ N

The force is 0.1040512455 N

tan\theta=\dfrac{55}{40}\\\Rightarrow \theta=tan^{-1}\dfrac{55}{40}\\\Rightarrow \theta=53.97^{\circ}

The angle the force makes is given by

\alpha=\theta-90\\\Rightarrow \alpha=53.97-90\\\Rightarrow \alpha=-36.03^{\circ}\ or\ 323.97^{\circ}in\ CCW\ direction

The direction is 36.03^{\circ}\ or\ 323.97^{\circ}in\ CCW\ direction

F=IlB\\\Rightarrow F=4.9\times \sqrt{20^2+35^2}\times 10^{-3}\times 0.3\\\Rightarrow F=0.05925\ N

The force is 0.05925 N

tan\theta=\dfrac{35}{20}\\\Rightarrow \theta=tan^{-1}\dfrac{35}{20}\\\Rightarrow \theta=60.26^{\circ}

\alpha=\theta-90\\\Rightarrow \alpha=60.26-90\\\Rightarrow \alpha=-29.74^{\circ}\ or\ 330.26^{\circ}in\ CCW\ direction

The direction is 29.74^{\circ}\ or\ 330.26^{\circ}in\ CCW\ direction

4 0
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