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Advocard [28]
3 years ago
5

A bus rolls to a stop along a horizontal road without the driver applying the brakes,

Physics
2 answers:
Nataly_w [17]3 years ago
5 0

Answer:

should be d because friction allows things to go faster or slower

klasskru [66]3 years ago
3 0
It’s opinion a I’m a 100%
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A particular X-ray photon has initial energy of 60 keV when it enters the body. This photon transmits through 30 cm of soft tiss
ankoles [38]

Answer:

E = 7.334 KeV

Explanation:

given,

initial energy = 60 keV

Δ x = 30 cm

E = E_0e^{-\mu \Delta x}

μ(for soft tissue) = 0.7 cm⁻¹ (taken from table)

E = E_0e^{-0.7\times 20}

         E = 60 × 0.1224

         E = 7.334 KeV

energy of x-ray photon after travelling through 30 cm soft tissue in body is E = 7.334 KeV

3 0
3 years ago
A pencil rolls horizontally of a 1 meter high desk and lands .25 meters from the base of the desk. How fast was the pencil rolli
vovikov84 [41]

Answer: 0.55 m/s

Explanation:

This situation is related to projectile motion (also called parabolic motion), where the main equations are as follows:

x=V_{o} cos\theta t (1)

y=y_{o}+Vo sin \theta t + \frac{g}{2}t^{2} (2)

Where:

x=0.25 m is the horizontal displacement of the pencil

V_{o} is the pencil's initial velocity

\theta=0\° since we are told the pencil rolls <u>horizontally</u> before falling

t is the time since the pencil falls until it hits the ground

y_{o}=1 m  is the initial height of the pencil

y=0  is the final height of the pencil (when it finally hits the ground)

g=-9.8m/s^{2}  is the acceleration due gravity, always acting vertically downwards

Begining with (1):

x=V_{o} cos(0\°) t (3)

x=V_{o}t (4)

Finding t from (2):

0=1 m+ \frac{-9.8m/s^{2}}{2}t^{2} (5)

t=\sqrt{\frac{-2y_{o}}{g}} (6)

Substituting (6) in (4):

x=V_{o}\sqrt{\frac{-2y_{o}}{g}} (7)

Isolating V_{o}:

V_{o}=\frac{x}{\sqrt{\frac{-2y_{o}}{g}}} (8)

V_{o}=\frac{0.25 m}{\sqrt{\frac{-2(1 m)}{-9.8m/s^{2}}}} (9)

Finally:

V_{o}=0.55 m/s

4 0
3 years ago
Indigenous people sometimes cooked in watertight baskets by placing enough hot rocks into the water to bring it to a boil. What
yaroslaw [1]

Answer:

The rock has a mass of 4.02 kg

Explanation:

<u>Step 1: </u>Data given

Mass of the rock = TO BE DETERMINED

Temperature of the rock = 500 °C

Mass of the water  =4.24 kg

⇒ loses 0.044kg as vapor

Initial temperature of the water = 29°C

Final temperature = 100°C

Specific heat of rock = 0.20 kcal/kg °C

Specific heat of water = 1kcal/kg°C

Latent heat of vaporization = 539 kcal/kg

<u>Step 2:</u> formules

Qlost,rock + Qgained,water = 0

Qtotal,water = Qwater +Qvapor

<u>Step 3: </u>Calculate Qvapor

Qvapor = mass of vapor * Latent heat of vapor

Qvapor = 0.044kg * 539 kcal/kg = 23.716 kcal

<u>Step 4: </u>Calculate Qwater

Qwater = mass of water * specific heat * Δtemperature

Qwater = 4.196 kg * 1kcal/kg°C *( 100-29)

Qwater = 297.916 kcal

<u>Step 5:</u> Calculate Qwater,total

Qwater,total = Qwater + Qvapor

Qwater,total = 23.716 kcal + 297.916 = 321.632 kcal

<u>Step 6</u>: Calculate Qrock

Qrock = mass of rock * specific heat rock * Δtemperature

Qrock = mass of rock * 0.20 kcal/kg°C * (100-500)

Qrock = mass of rock * -80 kcal/kg

<u>Step 7:</u> Calculate mass of rock

Qlost,rock + Qgained,water = 0

Qlost,rock = -Qgained,water

mass of rock * -80 kcal/kg = -321.632 kcal

mass of rock = 4.02 kg

The rock has a mass of 4.02 kg

7 0
2 years ago
A block of stone measures 15cm x 15cm x 20 cm.What is the total surface area of the stone
Sidana [21]

This should help look at the pictures?

7 0
3 years ago
What is your opinion on Moonman? ( Do not delete this saying it is "racist". it is simply a character from a commercial called M
Leni [432]

Answer:

I think hes cool

Explanation:

8 0
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