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3 years ago

Help please? thank you

Physics

1 answer:

Furkat [3]3 years ago

4 0

Hey!

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$\Large\boxed{\mathsf{D.~The~Ability~To~Do~Work}}$

In physics, energy is classified as doing some form of work. We classify energy as:

Chemical Energy
Thermal Energy
Potential Energy
Thermal Energy
Electrical Energy

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Hope This Helped! Good Luck!

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A sky diver with a mass of 70kg jumps from an aircraft. The aerodynamic drag force acting on the sky diver is known to be Fd=kV^

xeze [42]

Answer:

$v_{max}=52.38\frac{m}{s}$

$v_{100}=33.81$

Explanation:

the maximum speed is reached when the drag force and the weight are at equilibrium, therefore:

$\sum{F}=0=F_d-W$

$F_d=W$

$kv_{max}^2=m*g$

$v_{max}=\sqrt{\frac{m*g}{k}} =\sqrt{\frac{70*9.8}{0.25}}=52.38\frac{m}{s}$

To calculate the velocity after 100 meters, we can no longer assume equilibrium, therefore:

$\sum{F}=ma=W-F_d$

$ma=W-F_d$

$ma=mg-kv_{100}^2$

$a=g-\frac{kv_{100}^2}{m}$ (1)

consider the next equation of motion:

$a = \frac{(v_{x}-v_0)^2}{2x}$

If assuming initial velocity=0:

$a = \frac{v_{100}^2}{2x}$ (2)

joining (1) and (2):

$\frac{v_{100}^2}{2x}=g-\frac{kv_{100}^2}{m}$

$\frac{v_{100}^2}{2x}+\frac{kv_{100}^2}{m}=g$

$v_{100}^2(\frac{1}{2x}+\frac{k}{m})=g$

$v_{100}^2=\frac{g}{(\frac{1}{2x}+\frac{k}{m})}$

$v_{100}=\sqrt{\frac{g}{(\frac{1}{2x}+\frac{k}{m})}}$ (3)

$v_{100}=\sqrt{\frac{9.8}{(\frac{1}{2*100}+\frac{0.25}{70})}}$

$v_{100}=\sqrt{\frac{9.8}{(\frac{1}{200}+\frac{1}{280})}}$

$v_{100}=\sqrt{\frac{9.8}{(\frac{3}{350})}}$

$v_{100}=\sqrt{1,143.3}$

$v_{100}=33.81$

To plot velocity as a function of distance, just plot equation (3).

To plot velocity as a function of time, you have to consider the next equation of motion:

$v = v_0 +at$

as stated before, the initial velocity is 0:

$v =at$ (4)

joining (1) and (4) and reducing you will get:

$\frac{kt}{m}v^2+v-gt=0$

solving for v:

$v=\frac{ \sqrt{1+\frac{4gk}{m}t^2}-1}{\frac{2kt}{m} }$

Plots:

5 0

3 years ago

Two sticks are suspended on silk thread, electrified by charges of opposite sign. Is there a magnetic field around them? An elec

IRINA_888 [86]

ANSWER and EXPLANATION

We want to identify if there will be an electric field and a magnetic field around the two sticks electrified by charges of opposite signs.

An electric field is a physical field that surrounds electrically charged particles and exerts a force on other charged particles in the surrounding.

This implies that the presence of electric charges on both sticks generates electric fields on them. Since the two charges are opposite, the electric force acting on them will be attractive.

Hence, there is an electric field.

A stationary charged object produces an electric field, as explained above, but will only produce a magnetic field if there is a motion of the object.

Hence, except the two sticks are caused to move, there will be no magnetic field around them.

5 0

1 year ago

Which best summarizes the scientific process that led to our current understanding of DNA? Please help

solniwko [45]

The answer is B.)

This is because for years scientists have build up and found discoveries that led to recent discoveries brought by previous scientists.

Hope this helps

7 0

3 years ago

Read 2 more answers

A ball is thrown eastward into the air from the origin (in the direction of the positive x-axis). The initial velocity is 50 i +

nikklg [1K]

Answer:

The ball lands 154.3 ft from the origin at an angle of 13.6° from the eastern direction toward the south.

Explanation:

Hi there!

The position vector of the ball is described by the following equation:

r = (x0 + v0x · t + 1/2 · ax · t², y0 + v0y · t + 1/2 · ay · t², z0 + v0z · t + 1/2 · g · t²)

Where:

r = poisition vector of the ball at time t.

x0 = initial horizontal position.

v0x = initial horizontal velocity (eastward).

t = time.

ax = horizontal acceleration (eastward).

y0 = initial horizontal position.

v0y = initial horizontal velocity (southward).

ay = horizontal acceleration (southward)

z0 = initial vertical position.

v0z = initial vertical velocity.

g = acceleration due to gravity.

We have to find at which time the vertical component of the position vector is zero (the ball is on the ground) and then we can calculate the horizontal distance traveled by the ball at that time, using the equations of the horizontal components of the position vector.

Let´s place the origin of the system of reference at the throwing point so that x0 and y0 and z0 = 0.

y = z0 + v0z · t + 1/2 · g · t² (z0 = 0)

0 = 48 ft/s · t - 1/2 · 32 ft/s² · t²

0 = t (48 ft/s - 16 ft / s² · t) (t= 0, the origin point)

0 = 48 ft/s - 16 ft / s² · t

- 48 ft/s / -16 f/s² = t

t = 3.0 s

Now, we can calculate how much distance the ball traveled in that time.

First, let´s calculate the distance traveled in the eastward direction:

x = x0 + v0x · t + 1/2 · ax · t² (x0 = 0, ax = 0 there is no eastward acceleration)

x = 50 ft/s · 3 s

x = 150 ft

And now let´s calculate the distance traveled in southward direction:

y = y0 + v0y · t + 1/2 · ay · t² (y0 = 0 and v0y = 0, initially, the ball does not have a southward velocity).

y = 1/2 · ay · t²

y = 1/2 · (-8 ft/s²) · (3 s)²

y = -36 ft

Then, the final position vector will be:

r = (150 ft, -36 ft, 0)

The traveled distance is the magnitude of the position vector:

$|r| = \sqrt{(150ft)^{2} + (-36ft)^{2}} = 154.3 ft$

To calculate the angle, we have to use trigonometry (see attached figure):

cos angle = adjacent side / hypotenuse

cos α = x/r

cos α = 150 ft / 154.3 ft

α = 13.6°

The ball lands 154.3 ft from the origin at an angle of 13.5° from the eastern direction toward the south.

8 0

3 years ago

Gamma rays have more energy than X-rays. What else is true about gamma rays?

posledela

The answer is D. They have a higher frequency than X-rays.

Gamma-rays falls in the electromagnetic spectrum above, Gamma-rays have frequencies greater than 10¹⁸ cycles per second, or Hertz (Hz)

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2 years ago