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3 years ago

Energy conversion for a man stepping off a cliff

Physics

1 answer:

Vanyuwa [196]3 years ago

7 0

Man moving to step off - chemical potential energy to kinetic energy
Man falling- potential energy to kinetic energy

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a projectile whose masss is 10g is fired directly upward from ground level with an initial velocity of 1000m/s neglecting the ef

sammy [17]

Answer:

<em>The speed of the projectile when it impacts the ground is 1000 m/s</em>

Explanation:

<u>Vertical Launch</u>

When an object is launched vertically and upwards it starts to move at an initial speed vo, then the acceleration of gravity makes that speed to reduce until it reaches 0. The object has reached its maximum height. Then, it starts to move downwards in free fall, with initial speed zero and gradually increasing it until it reaches the ground level. We will demonstrate that the speed it has when impacts the ground is the same (and opposite) as the initial speed vo.

The speed when the object is moving upwards is given by

$v_f=v_o-g.t$

The time it takes to reach the maximum height is when vf=0, i.e.

$0=v_o-g.t$

solving for t

$\displaystyle t=\frac{v_o}{g}$

The maximum height reached is

$\displaystyle y=\frac{gt^2}{2}=\frac{v_o^2}{2g}$

Then, the object starts to fall. The object's height is given by

$\displaystyle y=\frac{v_o^2}{2g}-\frac{gt'^2}{2}$

where t' is the time the object has traveled downwards. The height will be 0 again when

$\displaystyle \frac{v_o^2}{2g}=\frac{gt'^2}{2}$

Solving for t'

$\displaystyle t'=\frac{v_o}{g}$

We can see the time it takes to reach the maximum height is the same it takes to return to ground level. Of course, the speed when it happens is

$v_f=g.t'=v_o$

Thus, the speed of the projectile when it impacts the ground is 1000 m/s

4 0

4 years ago

A sport car starts from rest with an acceleration of 12 m/s2 . Calculate its final velocity after 7 s.

miv72 [106K]

Answer:

Final velocity= 84 m/s

Explanation:

V final= V initial + a * t

Vf = 0+ 12 (7)

Vf= 84 m/s

4 0

3 years ago

How is a compound different than a mixture?

emmasim [6.3K]

The answer is: A compound can be separated by physical means.

5 0

3 years ago

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A proton experiences a force of 4 Newton when it enters perpendicular to the direction of the magnetic field with a speed 100 m/

____ [38]

Answer:

F = 0 N

Explanation:

Force on a moving charge in constant magnetic field is given by the formula

$F = q(\vec v\times \vec B)$

so here it depends on the speed of charge, magnetic field and the angle between velocity of charge and the magnetic field

here when charge is moving with speed 100 m/s in a given magnetic field then the force on the charge is given as

$F = 4 N$

now when charge is moving parallel to the magnetic field with different speed then in that case

$\vec v \time \vec B = 0$

so here we have

F = 0

7 0

3 years ago

In the photoelectric effect, it is found that incident photons with energy 5.00ev will produce electrons with a maximum kinetic

Yakvenalex [24]

From Literature:

The amount of energy in the photons is given by this equation:

E = hf

where E = energy
h = Planck's constant = 6.63 * 10^-34 Joule seconds
f = frequency of the light, Hz

Given:

E= 3.00 eV and Planck's constant

To solve for the frequency, E = 3.00 eV

1 electronvolt = 1.60218 x 10^-19 Joules

3 * 1.60218 x 10^-19 Joules = 6.63 * 10^-34 Joule seconds * f
f = 7.25 x 10^14 /second or hertz

Therefore, the threshold frequency of the material is 7.25 x 10^14 Hertz.

7 0

4 years ago

Read 2 more answers