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arsen [322]
2 years ago
4

Jessica stretches her arms out 0.8 m from the center of her body while holding a 2.0 kg mass in each hand. She then spins around

on an ice rink at 1.2 m/s.
a. What is the combined angular momentum of the masses?
b. If she pulls her arms in to 0.12 m, what is her new linear speed?
Physics
2 answers:
Alex73 [517]2 years ago
7 0

Answer:

54

Explanation:

Allushta [10]2 years ago
7 0

Answer:

a) L = 3.84 kg m² / s, b)   v = 0.96 m / s

Explanation:

a) the angular momentum is

    L = I w

Linear and angular magnitudes are related

     v = w r

     w = v / r

The moment of inertia of a point mass is

      I = m r²

We replace

     L = 2 m r² v / r

The two is because they are two masses

     L = 2 m r v

     L = 2 2.0 0.8 1.2

     L = 3.84 kg m² / s

b) The girl reduces the distance to 0.12 m

In this case the system is isolated, so the angular momentum is preserved

Initial moment,

       L₀ = 3.84 kg m² / s

Final after shrugging arms

       L_{f} = I  w_{f}

       L₀ =  L_{f}

      3.84 = 2 2.0 0.12 wf

       w_{f}  = 3.84 / 0.48

       w_{f}  = 8 rad / s

Linear velocity is

       v = w r

      v = 8 0.12

      v = 0.96 m / s

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If a rock is thrown upward on the planet mars with a velocity of 11 m/s, its height (in meters) after t seconds is given by h =
Butoxors [25]
(a) 3.56 m/s 
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For most of these problems, you're being asked the velocity of the rock as a function of t, while you've been given the position as a function of t. So first calculate the first derivative of the position function using the power rule. 
y = 11t - 1.86t^2 
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y' = 11 - 3.72t 
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(c) Use the quadratic formula to find the zeros for the position function y = 11t-1.86t^2. Roots are t = 0 and t = 5.913978495. The t = 0 is for the moment the rock was thrown, so the answer is t = 5.9 seconds.  
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2 years ago
A sister spins her brother in a circle of radius R at angular speed wi. Then the sister decreases her angular speed
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Answer:

The change in the centripetal acceleration of the brother,

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Explanation:

Given data,

A sister spins her brother in a circle of radius, R

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The angular velocity of the brother, ω₂ = V₂/R

The centripetal acceleration is given by the relation

                                 a = V²/R

Therefore change in the centripetal acceleration of the brother,

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