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3 years ago

Describe how cell membranes are selectively permeable

1 answer:

5 0

<span>Cell membranes are selectively permeable because it allows some things to enter or leave the cell while keeping other things outside or inside the cell.</span>

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Two trucks with equal mass are attracted to each other with a gravitational force of 5.3 x 10 -4 N. The trucks are separated by

HACTEHA [7]

Answer:

7327 kg or 7.3 tons

Explanation:

We have Newton formula for attraction force between 2 objects with mass and a distance between them:

$F_G = G\frac{M_1M_2}{R^2}$

where $G =6.67408*10^{-11} m^3/kgs^2$ is the gravitational constant on Earth. $M = M_1 = M_2$ is the masses of the 2 objects. and R = 2.6m is the distance between them.

$F_G = 5.3*10^{-4}N$ is the attraction force.

$5.3*10^{-4} = 6.67408*10^{-11}\frac{M^2}{2.6^2}$

$7941265 = \frac{M^2}{2.6^2}$

$M^2 = 53682948.76$

$M = \sqrt{53682948.76} \approx 7327 kg$ or 7.3 tons

3 0

4 years ago

An airplane travels at 300 mi/h south for 2.00 h and then at 250 mi/h north for 750 miles. What is the average speed for the tri

Anettt [7]

Answer:

270 mi/h

Explanation:

Given that,

To the south,

v₁ = 300 mi/h, t₁ = 2 h

We can find distance, d₁

$d_1=v_1\times t_1\\\\d_1=300\times 2\\\\d_1=600\ \text{miles}$

To the north,

v₂ = 250 mi/h, d₂ = 750 miles

We can find time, t₂

$t_2=\dfrac{d_2}{v_2}\\\\t_2=\dfrac{750\ \text{miles}}{250\ \text{mi/h}}\\\\t_2=3\ h$

Now,

Average speed = total distance/total time

$V=\dfrac{d_1+d_2}{t_1+t_2}\\\\V=\dfrac{600+750}{2+3}\\\\V=270\ \text{mi/h}$

Hence, the average speed for the trip is 270 mi/h.

3 0

3 years ago

Chase is trying to push a 120-kilogram boulder along the street. He applies a force of 1,115 newtons, and he does this over a di

lord [1]

Answer:

The work done is equal to zero = 0

Explanation:

Let us remember that the definition of physical work is given by the product of force by the displacement of the body.

$Work=F*d\\\\where\\F= force [N]\\d=distance [m]\\replacing\\Work=1115*(0) = 0$

4 0

3 years ago

Assume that you found that the average volume of water required to fill the graduated cylinder to the 8.00 ml mark was 7.70 ml.

Diano4ka-milaya [45]

<span>We convert the Fahrenheit temperature to Celsius. C = F 32 F 5 C = 15 F 32 F 5 C = 26 C . The antifreeze only protects to 9 F 9 F 22 C and thus it will not offer protection to temperatures as low as 15 F = 26.1 C . 2A (E) The mass is the difference between the mass of the full and empty flask. density = 291.4 g 108.6 g = 1.46 g/mL 125 mL 2B (E) First determine the volume required. V = (1.000 × 103 g) (8.96 g cm-3) = 111.6 cm3. Next determine the radius using the relationship between volume of a sphere and radius. 4 4 111.6 3 r= 3 = 2.987 cm V = r3 = 111.6 cm3 = (3.1416)r3 3 3 4(3.1416) 3A (E) The volume of the stone is the difference between the level in the graduated cylinder with the stone present and with it absent. density = mass 28.4 g rock = = 2.76 g/mL = 2.76 g/cm3 volume 44.1 mL rock &water 33.8 mL water 3B (E) </span>

5 0

3 years ago

A car traveling at a speed of 30 m/s encounters an emergency and comes to a complete

Natasha2012 [34]

Answer:

Explanation:

Use the one-dimensional equation

$v_f=v_0+at$ which says that the final velocity of an object is equal to the object's initial velocity plus its acceleration times time. We are looking for time. That means the equation looks like this:

0 = 30 + (-4)t and

-30 = -4t so

t = 7.5 sec

4 0

3 years ago