Physics, 30.03.2020 19:00 taynalizcaamanoxewm0

The specialty of an athlete on the women's track team is the pole vault. She has a mass of 60.0 kg and her approach speed is 9.20 m/s. When she is directly above the bar, her speed is 2.40 m/s. Neglecting air resistance and any energy absorbed by the pole, determine the amount she has raised herself as she crosses the bar.

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Answer from: sammizwang

She raised approximately 4 meters as she crosses the bar

Explanation:

Energy Conservation

In the absence of air resistance and any other energy-absorbing events, the total mechanical energy is conserved. Recall the mechanical energy is the sum of the gravitational potential energy and the kinetic energy:

$\displaystyle M=m.g.h+\frac{1}{2}m.v^2$

When our athlete is at the ground level her height is 0, thus she has only kinetic energy given by the speed she's at when starting the jump:

$\displaystyle M_1=m.g.(0)+\frac{1}{2}m.v^2=\frac{1}{2}m.v^2$

Later when she's directly above the bar, she has both energies since some speed remains at a certain height h we must calculate. The mechanical energy is

$\displaystyle M_2=m.g.h+\frac{1}{2}m.v'^2$

Equating both energies

$\displaystyle m.g.h+\frac{1}{2}m.v'^2=\frac{1}{2}m.v^2$

Simplifying by m and rearranging

$\displaystyle m.g.h=\frac{1}{2}m.v^2-\frac{1}{2}m.v'^2=\frac{1}{2}(v^2-v'^2)$

Solving for h

$\displaystyle h=\frac{(v^2-v'^2)}{2g}=\frac{(9.2^2-2.4^2)}{2\cdot 9.8}$

$\boxed{h=4.02\ m}$

She raised approximately 4 meters as she crosses the bar

Answer from: Quest

a) are muscles that have bands.

happy to

pls mark as brainliest

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

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The specialty of an athlete on the women's track team is the pole vault. She has a mass of 60.0 kg a...