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Bess [88]
3 years ago
7

The elastic energy stored in your tendons can contribute up to 35%% of your energy needs when running. Sports scientists find th

at (on average) the knee extensor tendons in sprinters stretch 41 mmmm while those of nonathletes stretch only 33 mmmm . The spring constant of the tendon is the same for both groups, 33 N/mmN/mm. Part A What is the difference in maximum stored energy between the sprinters and the nonathletes
Physics
1 answer:
zzz [600]3 years ago
4 0

Answer:

11.16 J

Explanation:

Elastic energy (E) stored in the tendon is given by 1/2ke^2

SPRINTERS

k = 31N/mm = 31N/mm × 1000mm/1m = 31,000N/m

e = 41mm = 41mm × 1m/1000mm = 0.041m

E = 1/2 × 31,000 × 0.041^2 = 26.06J

NON-ATHLETES

k = 31,000N/m

e = 31mm = 31mm × 1m/1000 = 0.031m

E = 1/2 × 31,000 × 0.031^2 = 14.90 J

Difference = 26.06 J - 14.90 J = 11.16 J

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A high-jump athlete leaves the ground, lifting her center of mass 1.8 m and crossing the bar with a horizontal velocity of 1.4 m
Romashka [77]

Answer:

The minimum speed when she leave the ground is 6.10 m/s.

Explanation:

Given that,

Horizontal velocity = 1.4 m/s

Height = 1.8 m

We need to calculate the minimum speed must she leave the ground

Using conservation of energy

K.E+P.E=P.E+K.E

\dfrac{1}{2}mv_{1}^2+0=mgh+\dfrac{1}{2}mv_{2}^2

\dfrac{v_{1}^2}{2}=gh+\dfrac{v_{2}^2}{2}

Put the value into the formula

\dfrac{v_{1}^2}{2}=9.8\times1.8+\dfrac{(1.4)^2}{2}

\dfrac{v_{1}^2}{2}=18.62

v_{1}=\sqrt{2\times18.62}

v_{1}=6.10\ m/s

Hence, The minimum speed when she leave the ground is 6.10 m/s.

6 0
3 years ago
What percentage of energy is available to organisms at each level of an energy pyramid?
Snowcat [4.5K]
The percentage of energy available to each organism is always 10 percent . 
6 0
3 years ago
A spinning ice skater will speed up if he brings his arms close to his body. Which of the following statements explains this phe
xxMikexx [17]
A. Angular momentum is always conserved would be the correct answer.

This is because like linear momentum (mvmv), angular momentum (r×mvr×mv) is a conserved quantity, where rr is the vector from the center of rotation. For a skater holding a static pose, for each particle making up her body, the contribution in magnitude to the total angular momentum is given by mirivimirivi. Thus bringing in her arms reduces riri for those particles. In order to conserve angular momentum, there is then an increase in the angular velocity.

hope this helps!
7 0
3 years ago
Read 2 more answers
An electromagnetic wave has a frequency of 1.0 x 10^5. What is the wavelength of the wave?
SashulF [63]

Answer:

The frequency , speed and wavelength of an electromagnetic wave are related by the formula

Speed = frequency x wavelength

frequency = speed / wavelength

substituting the values

frequency = 3 x #10 ^8# m /s / 1 x #10^15# m

= 3 x #10^-7# /s

6 0
2 years ago
Read 2 more answers
The current through an inductor of inductance L is given by I(t) = Imax sin(ωt).
sammy [17]

Answer:

(a) emf_L=-LI_{max}\omega cos(\omega t)

(b) neither increasing or decreasing

(c) opposite to the flow of charge carriers

Explanation:

The current through an inductor of inductance L is given by:

I(t)=I_{max}sin(\omega t)   (1)

(a) The induced emf is given by the following formula

emf_L=-L\frac{dI}{dt}    (2)

You derivative the expression (1) in the expression (2):

emf_L=-L\frac{d}{dt}(I_{max}sin(\omega t))\\\\emf_L=-LI_{max}\omega cos(\omega t)

(b) At t=0 the current is zero

(c) At t = 0 the emf is:

emf_L=-\omega LI_{max}

w, L and Imax have positive values, then the emf is negative. Hence, the induced emf is opposite to the flow of the charge carriers.

(d) read the text carefully

6 0
3 years ago
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