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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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An object thrown vertically upward from the surface of a celestial body at a velocity of 36 m/s reaches a height of sequalsminu

Anarel [89]

Answer:

v = -1.8t+36

20 seconds

360 m

40 seconds

36 m/s

The object speed will increase when it is coming down from its highest height.

Explanation:

$s=-0.9t^2+36t$

Differentiating with respect to time we get

$\frac{ds}{dt}=-1.8t+36\\\Rightarrow v=-1.8t+36$

a) Velocity of the object after t seconds is v = -1.8t+36

At the highest point v will be 0

$0=-1.8t+36\\\Rightarrow t=\frac{-36}{-1.8}\\\Rightarrow t=20\ s$

b) The object will reach the highest point after 20 seconds

$s=-0.9t^2+36t\\\Rightarrow s=-0.9\times 20^2+36\times 20\\\Rightarrow s=360\ m$

c) Highest point the object will reach is 360 m

$s=-0.9t^2+36t\\\Rightarrow 360=-0.9t^2+36t\\\Rightarrow -0.9t^2+36t-360=0\\\Rightarrow -9t^2+360t-3600=0$

$\frac{-360\pm \sqrt{0}}{2\left(-9\right)}\\\Rightarrow t=20\ s$

d) Time taken to strike the ground would be 20+20 = 40 seconds

$[tex]v=u+at\\\Rightarrow v=0+0.9\times 2\times 20\\\Rightarrow v=36\ m/s$

Acceleration will be taken as positive because the object is going down. Hence, the sign changes. 2 is multiplied because the expression is given in the form of $s=ut+\frac{1}{2}at^2$

e) The velocity with which the object strikes the ground will be 36 m/s

f) The speed will increase when the object has gone up and for 20 seconds and falls down for 20 seconds. The object speed will increase when it is coming down from its highest height.

4 0

3 years ago

The light from the sun has higher frequencies from one side of the sun than from the other side. What does that tell you about t

morpeh [17]

If the light from the sun has higher frequencies from one side of the sun than from the other side, it is proof that the Sun is rotating.

Doppler effect states that, if a person is standing still and a source ( sound / light ) is moving towards him, the frequency of the wave emitted from the object will increase and if the source ( sound / light ) is away from him, the frequency of the wave emitted from the object will decrease.

So, if the light from the sun has higher frequencies from one side of the sun than from the other side, it means that the Sun is rotating. The higher frequencies points are the points that rotating towards Earth and lower frequencies points are the points that rotating away from Earth.

Therefore, if the light from the sun has higher frequencies from one side of the sun than from the other side, it is proof that the Sun is rotating.

To know more about Doppler Effect

brainly.com/question/15318474

#SPJ1

8 0

1 year ago

Which of the following terms is best described as the number of waves that pass a point in one second? A) wave speed B) period C

ehidna [41]

The term that best describes how many waves that pass? It's frequency because how many waves are passed by a given point or time is called the waves frequency. I hope this helped you out on your assignment.

3 0

3 years ago

Which describes a condition of the neritic zone?

Lady_Fox [76]

Answer:

So frigid temps I think .

Explanation:

The neritic zone is a shallow zone of water. It is sunlit and it receives ample solar insolation all year round. The salinity of this zone is very stable. This makes for organism to thrive. The neritic zone is home to diverse aquatic life.

3 0

3 years ago

Read 2 more answers

Please help me

RSB [31]

The potentially harmful effects of mining can be reduced by A. Flushing mines with water.

5 0

3 years ago