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3 years ago

Why are potassium molecules likely to enter a red blood cell?

1 answer:

5 0

<span>they have to be selective permeable to filter out the waste products but allow the nutrients and blood cells to pass through. </span>

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A machine does 1200 J of work in 1 min. What is the power developed

densk [106]

Answer:

20 watts

Explanation:

Big brain mode activated:

Power=1200J/60sec

Power=20 watts

8 0

3 years ago

Which of the following statements must be true if the net force on an object is zero? Choose all that apply.

Black_prince [1.1K]

Answer:

a) The object must have constant velocity.

d) The object must have zero acceleration.

Explanation:

We can solve the problem by using Newton's second law, which states that the net force acting on an object is equal to the product between mass and acceleration:

$F = ma$

where

F is the net force

m is the mass of the object

a is the acceleration

In this problem, the net force on the object is zero:

F = 0

This means that the acceleration of the object is also zero, according to the previous equation:

a = 0

So statement (d) is correct. Moreover, acceleration is defined as the rate of change of velocity:

$a=\frac{\Delta v}{\Delta t}$

Which means that $\Delta v=0$ , so the velocity is constant. Therefore, statement (a) is also correct. The other two statements are false because:

b)The object must be at rest. --> false, the object can be moving at constant velocity, different from zero

c)The object must be at the origin. --> false, since the object can be in motion

5 0

3 years ago

In a Broadway performance, an 77.0-kg actor swings from a R = 3.65-m-long cable that is horizontal when he starts. At the bottom

krek1111 [17]

Answer: h =1.22 m

Explanation:

from the question we were given the following

mass of performer ( M1 ) = 77 kg

length of cable ( R ) = 3.65 m

mass of costar ( M2 ) = 55 kg

maximum height (h) = ?

acceleration due to gravity (g) = 9.8 m/s^2 (constant value)

We first have to find the velocity of the performer. From the work energy theorem work done = change in kinetic energy

work done = 1/2 x mass x ( (final velocity)^2 - (initial velocity)^2 )

initial velocity is zero in this case because the performer was at rest before swinging, therefore

work done = 1/2 x 77 x ( v^2 - 0)

work done = 38.5 x ( v^2 ) ......equation 1

work done is also equal to m x g x distance ( the distance in this case is the length of the rope), hence equating the two equations we have

m x g x R = 38.5 x ( v^2 )

77 x 9.8 x 3.65 = 38.5 x ( v^2 )

2754.29 = 38.5 x ( v^2 )

( v^2 ) = 71.54

v = 8.4 m/s ( velocity of the performer)

After swinging, the performer picks up his costar and they move together, therefore we can apply the conservation of momentum formula which is

initial momentum of performer (P1) + initial momentum of costar (P2) = final momentum of costar and performer after pick up (Pf)

momentum = mass x velocity therefore the equation above now becomes

(77 x 8.4) + (55 x 0) = (77 +55) x Vf

take note the the initial velocity of the costar is 0 before pick up because he is at rest

651.3 = 132 x Vf

Vf = 4.9 m/s

the performer and his costar is 4.9 m/s after pickup

to finally get their height we can use the energy conservation equation for from after pickup to their maximum height. Take note that their velocity at maximum height is 0

initial Kinetic energy + Initial potential energy = Final potential energy + Final Kinetic energy

where

kinetic energy = 1/2 x m x v^2

potential energy = m x g x h

after pickup they both will have kinetic energy and no potential energy, while at maximum height they will have potential energy and no kinetic energy. Therefore the equation now becomes

initial kinetic energy = final potential energy

(1/2 x (55 + 77) x 4.9^2) + 0 = ( (55 + 77) x 9.8 x h) + 0

1584.7 = 1293 x h

h =1.22 m

3 0

4 years ago

How much time does it take for a spinning baseball with an angular speed of 38 rad/s to rotate through 15 degrees

Nadusha1986 [10]

Answer:

the time of motion of the ball is 6.89 ms.

Explanation:

Given;

angular speed, ω = 38 rad/s

angular distance, θ = 15 degrees

Angular distance in radian;

$\theta = 15^0 \times\frac{2\pi \ rad}{360^0} = 0.2618 \ rad$

Time of motion is calculated as;

$time = \frac{angular \ distance}{angular \ speed} \\\\t= \frac{\theta}{\omega} = \frac{0.2618 \ rad}{38 \ rad/s} \\\\t = 6.89 \ \times 10^{-3} \ s\\\\t = 6.89 \ ms$

Therefore, the time of motion of the ball is 6.89 ms.

3 0

3 years ago

Data that consists of numbers and measurements is called __________ data.

Vsevolod [243]

<span>Quantitative. I hopes this helps you some!</span>

8 0

3 years ago

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