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2 years ago

How do the lens of a light microscope work

1 answer:

8 0

The smallest one is the least powerful one. And the medium size one is the medium powerful one. And the largest one is the most powerful one of them all

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Which body exerts the force that propels the sprinter, the blocks or the sprinter?

kicyunya [14]

Answer: The blocks

Explanation:
When the sprinter takes off, he/she presses hard on the block.
The blocks apply an equal and opposite force to the sprinter according to Newton's 3rd law of motion.
The reaction force from the blocks gives the sprinter the initial acceleration to begin the race.

5 0

3 years ago

When a car's velocity is positive and its acceleration is negative, what is happening to the car's motion?

Novosadov [1.4K]

Answer:

Assuming rightward is positive, the velocity is positive whenever the car is moving to the right, and the velocity is negative whenever the car is moving to the left. The acceleration points in the same direction as the velocity if the car is speeding up, and in the opposite direction if the car is slowing down.

Explanation:

8 0

3 years ago

Calculate the unit cell edge length for an 79 wt% Ag- 21 wt% Pd alloy. All of the palladium is in solid solution, and the crysta

ankoles [38]

Answer:

The edge length is 0.4036 nm

Solution:

As per the question:

Density of Ag, $\rho = 10.49 g/cm^{3}$

Density of Pd, $\rho = 12.02 g/cm^{3}$

Atomic weight of Ag, A = 107.87 g/mol

Atomic weight of Pd, A' = 106.4 g/mol

Now,

The average density, $\rho_{a} = \frac{n A_{avg}} {V_{c}\times N_{A}}$

where

$V_{c} = a^{3}$ = Volume of crystal lattice

a = edge length

n = 4 = no. of atoms in FCC

Therefore,

$\rho_{a} = = \frac{n A_{avg}} {V_{c}\times N_{A}}$

Therefore, the length of the unit cell is given as:

$a = (\frac{nA_{avg}}{\rho_{a}\times N_{a}})^{1/3}$ (1)

Average atomic weight is given as:

$A_{avg} = \frac{100}{\frac{C_{Ag}}{A_{Ag}} + \frac{C_{Pd}}{A_{Pd}}}$

where

$C_{Ag}$ = 79 %

$A_{Ag}$ = 107

$C_{Pd}$ = 21%

$A_{Pd}$ = 106

Therefore,

$A_{avg} = \frac{100}{\frac{79}{107} + \frac{21}{106}} = 106.78$

In the similar way, average density is given as:

$\rho_{a} = \frac{100}{\frac{C_{Ag}}{\rho_{Ag}} + \frac{C_{Pd}}{\rho_{Pd}}}$

$\rho_{a} = \frac{100}{\frac{79}{10.49} + \frac{21}{12.02}} = 10.78 g/cm^{3}$

Therefore, edge length is given by eqn (1) as:

$a = (\frac{4\times 106.78}{10.78\times 6.023 X 10^23})^{1/3} = 4.036\times 10^{- 8} cm = 0.4036\times 10^{- 9} m = 0.4036 nm$

5 0

3 years ago

You are designing an airport for small planes. One kind of airplane that might use this airfield must reach a speed before takeo

ladessa [460]

Explanation:

Given that,

Initial speed of the airfield, u = 0

Final speed, v = 27.8 m/s

Acceleration of the airfield, $a=2\ m/s^2$

Length of the runway, d = 150 m

Let v' is the speed of the airplane to reach the required speed for takeoff. Finding v' using third equation of motion as :

$v'^2-u^2=2ad\\\\v'=\sqrt{2ad} \\\\v'=\sqrt{2\times 2\times 150} \\\\v'=24.49\ m/s$

This speed is not enough as the airfield must reach a speed before takeoff of at least 27.8 m/s. Now, the required length of the runways is :

$v^2=2ax\\\\x=\dfrac{v^2}{2a}\\\\x=\dfrac{(27.8)^2}{2\times 2}\\\\x=193.21\ m$

So, the minimum length of the runways is 193.21 meters.

8 0

3 years ago

Which combination of temperature and pressure correctly describes standard temperature and pressure

raketka [301]

Answer: A combination 0 degrees Celsius and 101.3 kPa or 1 atm correctly describes standard temperature and pressure.

Explanation:

The term standard temperature and pressure is also known as STP and it is most commonly used when we want to calculate the density of a gas.

The term standard temperature means $32^{o}$ Fahrenheit or $0^{o}C$ or 273 Kelvin. On the other hand, term standard pressure means 1 atmosheric pressure of a gas.

Thus, we can conclude that a combination 0 degrees Celsius and 101.3 kPa or 1 atm correctly describes standard temperature and pressure.

4 0

3 years ago