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3 years ago

HEY PLEASE HELP AM DESPERATE!!!!!!

Physics

2 answers:

MariettaO [177]3 years ago

4 0

Answer:

Runner A

Explanation:

Both B and C finished the race from 25 seconds

But A runner finished it from 20 seconds

MAVERICK [17]3 years ago

3 0

Answer:

runner A is win

Explanation:

because he take smallest time

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Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it

elena55 [62]

Answer:An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.

Explanation:

5 0

3 years ago

Read 2 more answers

A fireman of 80 kg slides down a pole.When he reaches the bottom, 4.2 m below his starting point, his speed is 2.2 m/s . By how

levacccp [35]

Answer:

3099 J

Explanation:

The increase in thermal energy corresponds to the mechanical energy lost in the process.

The mechanical energy is given by the sum of gravitational potential energy and kinetic energy of the fireman:

$E=K+U$

At the top of the pole, the fireman has no kinetic energy, so all his mechanical energy is just potential energy:

$E=U=mgh=(80 kg)(9.8 m/s^2)(4.2 m)=3293 J$

When the fireman reaches the bottom, he has no gravitational potential energy, so his mechanical energy is just given by his kinetic energy:

$E=K=\frac{1}{2}mv^2=\frac{1}{2}(80 kg)(2.2 m/s)^2=194 J$

So, the loss in mechanical energy was

$\Delta E=3293 J-194 J=3099 J$

and this corresponds to the increase in thermal energy.

7 0

3 years ago

A horizontal circular platform rotates counterclockwise about its axis at the rate of 0.945 rad/s. You, with a mass of 69.7 kg,

pickupchik [31]

Answer:

317.22

Explanation:

Given

Circular platform rotates ccw 93.1kg, radius 1.93 m, 0.945 rad/s

You 69.7kg, cw 1.01m/s, at r

Poodle 20.2 kg, cw 1.01/2 m/s, at r/2

Mutt 17.7 kg, 3r/4

You

Relative

ω = v/r

= 1.01/1.93

= 0.522

Actual

ω = 0.945 - 0.522

= 0.42

I = mr^2

= 69.7*1.93^2

= 259.6

L = Iω

= 259.6*0.42

= 109.4

Poodle

Relative

ω = (1.01/2)/(1.93/2)

= 0.5233

Actual

ω = 0.945- 0.5233

= 0.4217

I = m(r/2)^2

= 20.2*(1.93/2)^2

= 18.81

L = Iω

= 18.81*0.4217

= 7.93

Mutt

Actual

ω = 0.945

I = m(3r/4)^2

= 17.7(3*1.93/4)^2

= 37.08

L = Iω

= 37.08*0.945

= 35.04

Disk

I = mr^2/2

= 93.1(1.93)^2/2

= 173.39

L = Iω

= 173.39*0.945

= 163.85

Total

L = 109.4+ 7.93+ 36.04+ 163.85

= 317.22 kg m^2/s

4 0

4 years ago

You are moving at a speed 2/3 c toward randy when randy shines a light toward you. at what speed do you see the light approachin

yarga [219]

I see the light moving exactly at speed equal to c.

In fact, the second postulate of special relativity states that:
"The speed of light in free space has the same value c in all inertial frames of reference."

The problem says that I am moving at speed 2/3 c, so my motion is a uniform motion (constant speed). This means I am in an inertial frame of reference, so the speed of light in this frame must be equal to c.

3 0

3 years ago

Niobium metal becomes a superconductor when cooled below 9 K. Its superconductivity is destroyed when the surface magnetic field

morpeh [17]

To develop the problem it is necessary to apply the concepts related to Magnetic Field.

The magnetic field is defined as

$B = \frac{\mu_0 I}{2\pi r}$