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pishuonlain [190]

4 years ago

10

A scientist views an unknown cell under a microscope. Which of the following observations would support the claim that it is a p

lant cell rather than an animal cell? Choose 1 answer: (Choice A) A It has a cell membrane. (Choice B) B It has chloroplasts. (Choice C) C It is round in shape. (Choice D) D It has a nucleus.

2 answers:

Mashutka [201]4 years ago

6 0

Answer:

Choice A. It has chloroplast

Plants have chloroplast and animals dont

Explanation:

alisha [4.7K]4 years ago

5 0

Answer:

Explanation:

Sorry I can’t give you an exact answer, but it is it is either A or D hope this helps!

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A student measures the diameter of a small cylindrical object and gets the following readings: 4.32, 4.35, 4.31, 4.36, 4.37, 4.3

Zinaida [17]

Answer:

a. $\bar{d}=4.34 cm$

b. $\sigma=0.023 cm$

c. $\rho=(0.0089\pm 0.00058) kg/cm^{3}$

Explanation:

a) The average of this values is the sum each number divided by the total number of values.

$\bar{d}=\frac{\Sigma_{i=1}^(N)x_{i}}{N}$

$x_{i}$ is values of each diameter
N is the total number of values. N=6

$\bar{d}=\frac{4.32+4.35+4.31+4.36+4.37+4.34}{6}$

$\bar{d}=4.34 cm$

b) The standard deviation equations is:

$\sigma=\sqrt{\frac{1}{N}\Sigma^{N}_{i=1}(x_{i}-\bar{d})^{2}}$

If we put all this values in that equation we will get:

$\sigma=0.023 cm$

Then the mean diameter will be:

$\bar{d}=(4.34\pm 0.023)cm$

c) We know that the density is the mass divided by the volume (ρ = m/V)

and we know that the volume of a cylinder is: $V=\pi R^{2}h$

Then:

$\rho=\frac{m}{\pi R^{2}h}$

Using the values that we have, we can calculate the value of density:

$\rho=\frac{1.66}{3.14*(4.34/2)^{2}*12.6}=0.0089 kg/cm^{3}$

We need to use propagation of error to find the error of the density.

$\delta\rho=\sqrt{\left(\frac{\partial\rho}{\partial m}\right)^{2}\delta m^{2}+\left(\frac{\partial\rho}{\partial d}\right)^{2}\delta d^{2}+\left(\frac{\partial\rho}{\partial h}\right)^{2}\delta h^{2}}$

δm is the error of the mass value.
δd is the error of the diameter value.
δh is the error of the length value.

Let's find each partial derivative:

1. $\frac{\partial\rho}{\partial m}=\frac{4m}{\pi d^{2}h}=\frac{4*1.66}{\pi 4.34^{2}*12.6}=0.0089$

2. $\frac{\partial\rho}{\partial d}=-\frac{8m}{\pi d^{3}h}=-\frac{8*1.66}{\pi 4.34^{3}*12.6}=-0.004$

3. $\frac{\partial\rho}{\partial h}=-\frac{4m}{\pi d^{2}h^{2}}=-\frac{4*1.66}{\pi 4.34^{2}*12.6^{2}}=-0.00071$

Therefore:

$\delta\rho=\sqrt{\left(0.0089)^{2}*0.05^{2}+\left(-0.004)^{2}*0.023^{2}+\left(-0.00071)^{2}*0.5^{2}}$

$\delta\rho=0.00058$

So the density is:

$\rho=(0.0089\pm 0.00058) kg/cm^{3}$

I hope it helps you!

3 0

3 years ago

Josh has a toy car of mass 3 kg tied to a string of length 2 m. He ties the string to a pole and has the toy car drive in a circ

gulaghasi [49]

Part a)

Centripetal acceleration is defined as

$a_c = \frac{v^2}{R}$

now here we know that

$v = 3m/s$

$R = 2 m$

m = 3 kg

now from above formula we have

$a_c = \frac{3^2}{2}$

$a_c = 4.5 m/s^2$

Part b)

Maximum possible tension in the string is given as

$T = 50 N$

now by force equation we have

$F = ma$

$50 = 3 a$

$a = \frac{50}{3} m/s^2$

now again by above formula

$\frac{v^2}{R} = \frac{50}{3}$

$v = \sqrt{\frac{50 \times 2}{3}}$

$v = 5.77 m/s$

5 0

4 years ago

Read 2 more answers

Communication with submerged submarines via radio waves is difficult because seawater is conductive and absorbs electromagnetic

REY [17]

Answer:

$\lambda=4000\ km$

Explanation:

It is given that,

Frequency for submarine communications, f = 76 Hz

We need to find the wavelength of those extremely low-frequency waves. the relation between the wavelength and the frequency is given by :

$c=f\times \lambda$

$\lambda=\dfrac{c}{f}$

$\lambda=\dfrac{3\times 10^8\ m/s}{76\ Hz}$

$\lambda=3947368.42\ m$

$\lambda=3947\ km$

or

$\lambda=4000\ km$

So, the wavelength of those extremely low-frequency waves is 4000 km. Hence, this is the required solution.

4 0

3 years ago

Dez pours water (n 1.333) into a container made of crown glass (n 1.52). The light ray in ner made of crown glass (n = 1.52). Th

siniylev [52]

Answer:

The angle of the corresponding refracted ray is 34.84°

Explanation:

Given that,

Refractive index of water n= 1.33

Refractive index of glass n= 1.52

Incident angle = 30.0°

We need to calculate the refracted angle

Using formula of Snell's law

$n_{i}\sin i=n_{r}\sin r$

Put the value into the formula

$\sin r=\dfrac{n_{i}\sin i}{n_{r}}$

$\sin r=\dfrac{1.52\times\sin30}{1.33}$

$\sin r=0.5714$

$r=sin^{-1}0.5714$

$r = 34.84^{\circ}$

Hence, The angle of the corresponding refracted ray is 34.84°

8 0

4 years ago

How much time does it take light to travel from the moon to the earth, a distance of 384000 km?

Natali5045456 [20]

Answer:

1.28second

Explanation:

The speed of light is constant everywhere, it is

299,792,458m/s=299,792.458km/s

Therefore it takes

$\frac{384000}{299792458} = 1.28sec$

6 0

1 year ago