Which statements are true about the flow of blood in the body? Check all that apply.

Can and object have a negative position and a positive velocity? Or vice versa, a positive position and a negative velocity? Exp

zavuch27 [327]

Imagine a ball is moving on the following horizontal line.

. . . . . . . . . . . . . . . . . . . O. . . . . . . . . . . . . . . . . .

Take right as positive. O is the starting point of the ball. Denote the ball by o.

. . . . . . . . . . . . . . . . . . . O. . . . . . . ... . . o . . . . . .

Assume the ball is moving to the right. It has positive displacement since it is on the right of O, and positive velocity since its positive displacement is increasing.

.ñ

. . . . . . . . . . . . . . . . . . . O. . . . o . . . . . . . . . . . . .

Now the ball is returning to O. It still has positive displacement since its current position is still on the right of O. However, its velocity is negative since its positive displacement is decreasing and the direction of the velocity vector points left, which is the negative side.

By now you should be able to come up with a scenario where the ball has negative displacement and positive velocity.

You can observe the same phenomenon in daily life. Say, as a stretched spring bounces to its starting position, if we let the returning direction be positive, the string has negative displacement since it is on the negative direction, but has positive velocity. Bungee jump can also used to illustrate the phenomenon.

4 0

2 years ago

Ammonia enters the expansion valve of a refrigeration system at a pressure of 10 bar and a temperature of 22oC and exits at 2.0

KonstantinChe [14]

Answer:

The the quality of the refrigerant at the exit of the expansion valve is 0.179.

Explanation:

Given that,

Initial pressure = 10 bar

Temperature = 22°C

Final pressure = 2.0 bar

We using the value of h

$h = 293.4\ kJ/kg$

The refrigerant during expansion undergoes a throttling process

Therefore, $h_{1}=h_{2}$

We need to calculate the quality of the refrigerant at the exit of the expansion valve

At 2.0 bar,

The property of ammonia

$h_{f}=47.8 kJ/kg$

$h_{g}=1417.7 kJ/kg$

Using formula

$h_{2}=h_{f}+x(h_{g}-h_{f})$

Put the value into the formula

$293.4 =47.8+x(1417.7-47.8)$

$x=\dfrac{293.4-47.8}{1417.7-47.8}$

$x=0.179$

Hence, The the quality of the refrigerant at the exit of the expansion valve is 0.179.

6 0

3 years ago

Consider the following four objects: a hoop, a solid sphere, a flat disk, a hollow sphere. Each of the objects has mass M and ra

Svetlanka [38]

Answer:

Hoop.

Explanation:

The angular acceleration performed at a given torque:

$\alpha = \frac{\tau}{I}$

The moments of inertia of each element are described below:

Hoop

$I = M\cdot R^{2}$

Solid sphere

$I = \frac{2}{5}\cdot M \cdot R^{2}$

Flat disk

$I = \frac{1}{2}\cdot M \cdot R^{2}$

Hollow sphere

$I = \frac{2}{3}\cdot M \cdot R^{2}$

The greater the moment of inertia, the greater the torque to obtain the same angular acceleration. Therefore, the hoop requires the largest torque to receive the same angular acceleration.

8 0

3 years ago

Wayne wants to become a lifeguard. For part of the lifeguard test, he has to float in the pool for five minutes. Why does Wayne

Nastasia [14]

Answer:

D

Explanation:

The gravity is pushing the water downward so Wayne could go down but the water is pushing Wayne to go up which would make him float.

6 0

3 years ago

Dans un tube en U contenant du mercure ,on verse de l'autre côté de l'acide sulfurique de densité 1,84 et de l'autre côté de l'a

Iteru [2.4K]

Explanation:

Unclear question. The clear rendering reads;

"Into a U-tube containing mercury, pour on the other side sulfuric acid of density 1.84 and on the other side alcohol of density 0.8 so that the levels are in the same horizontal plane. The height of the acid above the mercury being 24 cm. What is the height of the bar and what variation of the level of the acid, when the mercury density is 13.6?

6 0

3 years ago