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Sergio [31]
2 years ago
7

A soccer player swings his leg forward to kick the ball. If his leg has a moment of inertia of 0.9 kg m2, and is initially at re

st, how much torque must he generate with his hip flexor muscle in order to reach an angular velocity of -8 rad/s in 0.5 seconds?
Physics
1 answer:
Usimov [2.4K]2 years ago
7 0

Answer:

14.4 Nm

Explanation:

Moment of Inertia, I = 0.9 kg m^2, w0 = 0, w = 8 rad/s, t = 0.5 second

Use first equation of motion for rotational motion

w = w0 + α t

where, α be the angular acceleration

8 = 0 + α x 0.5

α = 16 rad/s^2

Now Torque = Moment of inertia x angular acceleration

τ = I x α

τ = 0.9 x 16 = 14.4 Nm

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(a) 3.56 m/s 
(b) 11 - 3.72a 
(c) t = 5.9 s 
(d) -11 m/s  
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 
y' = 11 - 3.72t 
Now that you have the first derivative, it will give you the velocity as a function of t. 
(a) Velocity after 2 seconds. 
y' = 11 - 3.72t 
y' = 11 - 3.72*2 = 11 - 7.44 = 3.56 
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(b) Velocity after a seconds. 
y' = 11 - 3.72t 
y' = 11 - 3.72a  
So the answer is 11 - 3.72a  
(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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y' = 11 - 3.72a
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3 0
2 years ago
Last year a baseball player made 63 errors. This year he made 42. What percent decrease was there in the number of errors commit
Crank

Answer:

33.33 %

Explanation:

given,

error last year = 63

error this year = 42

percent decrease in the error = ?

to find the percentage difference in the error formula used is

   = \dfrac{difference}{original}\times 100

   = \dfrac{63-42}{63}\times 100

   = \dfrac{21}{63}\times 100

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Percentage decrease in the number of error is equal to 33.33%.

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2 years ago
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Alina [70]

Answer:

the correct statement is the first

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Explanation:

The law of conservation of energy establishes that the masses are not destroyed, they can only be transformed.

Therefore the mass of carbon in the reactants (CO2 and H2O) must be in the products (glucose and oxygen)

so the correct statement is the first

The law of conservation of mass indicates the same amount of carbon will be found in the reactants as in the products.

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Explanation:

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You are on vacation in San Francisco and decide to take a cable car to see the city. A 5800-kgkg cable car goes 260 mm up a hill
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where, g = acceleration due to gravity

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2 years ago
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