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3 years ago

How much physical activity do adults need

1 answer:

5 0

For most healthy adults, the Department of Health and Human Services recommends these exercise guidelines: Aerobic activity. Get at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of vigorous aerobic activity. You also can do a combination of moderate and vigorous activity.

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A wave is incident on the surface of a mirror at an angle of 41° with the normal. what can you say about its angle of reflection

Umnica [9.8K]

It's angle of reflection must be 41 degrees

we know, by the first law of reflection that angle of incidence is always equal to angle of reflection..........

7 0

3 years ago

Read 2 more answers

A brick lands 10.1 m from the base of a building. If it was given an initial velocity of 8.6 m/s [61º above the horizontal], how

Montano1993 [528]

<h2>Answer: 10.52m</h2><h2 />

First, we have to establish the <u>reference system</u>. Let's assume that the building is on the negative y-axis and that the brick was thrown at the origin (see figure attached).

According to this, the initial velocity $V_{o}$ has two components, because the brick was thrown at an angle $\alpha=61\º$ :

$V_{ox}=V_{o}cos\alpha$ (1)

$V_{ox}=8.6\frac{m}{s}cos(61\º)=4.169\frac{m}{s}$ (2)

$V_{oy}=V_{o}sin\alpha$ (3)

$V_{oy}=8.6\frac{m}{s}sin(61\º)=7.521\frac{m}{s}$ (4)

As this is a projectile motion, we have two principal equations related:

$X=V_{ox}.t$ (5)

Where:

$X=10.1m$ is the distance where the brick landed

$t$ is the time in seconds

If we already know $X$ and $V_{ox}$ , we have to find the time (we will need it for the following equation):

$t= \frac{X}{ V_{ox}}$ (6)

$t=2.42s$ (7)

$-y=V_{oy}.t+\frac{1}{2}g.t^{2}$ (8)

Where:

$y$ is the height of the building (<u>in this case it has a negative sign because of the reference system we chose)</u>

$g=-9.8\frac{m}{s^{2}}$ is the acceleration due gravity

Substituting the known values, including the time we found on equation (7) in equation (8), we will find the height of the building:

$-y=(7.521\frac{m}{s})(2.42s)+\frac{1}{2}(-9.8\frac{m}{s^{2}}).(2.42s)^{2}$ (9)

$-y=-10.52m$ (10)

Multiplying by -1 each side of the equation:

$y=10.52m$ >>>>This is the height of the building

3 0

3 years ago

The boiling point of sulfur is 444.6 celsius .sulfur melting point is 586.1 fahrenheit lower than its boiling?

iVinArrow [24]

Answer:

(a) Melting point is 136.8°C

(b) Melting point is 278.24°F

Boiling point is 832.28°F

Boiling point is 717.6K

Explanation:

(a) 586.1°F = 5/9(586.1 - 32)°C = 307.8°C

Melting point = 444.6°C - 307.8°C = 136.8°C

(b) Melting point = 136.8°C = (9/5×136.8) + 32 = 278.24°F

Boiling point = 444.6°C = (9/5×444.6) + 32 = 832.28°F

Boiling point = 444.6°C = 444.6 + 273 = 717.6K

8 0

3 years ago

. One long wire carries a current of 30 A along the entire x axis. A second-long wire carries a current of 40 A perpendicular to

d1i1m1o1n [39]

Answer:

magnitude of net magnetic field at given point is

$B = 5 \times 10^{-6} T$

Explanation:

As we know that magnetic field due to a long current carrying wire is given as

$B = \frac{\mu_o i}{2\pi r}$

here we we will find the magnetic field due to wire which is along x axis is given as

$i = 30 A$

r = 2 m

now we have

$B_1 = \frac{4\pi \times 10^{-7} (30)}{2\pi (2m)}$

$B_1 = 3\times 10^{-6} T$ into the plane

Now similarly magnetic field due to another wire which is perpendicular to xy plane is given as

$i = 40 A$

r = 2 m

now we have

$B_2 = \frac{4\pi \times 10^{-7} (40)}{2\pi (2m)}$

$B_2 = 4\times 10^{-6} T$ along + x direction

Since the two magnetic field is perpendicular to each other

So here net magnetic field is given as

$B = \sqrt{B_1^2 + B_2^2}$

$B = 5 \times 10^{-6} T$

5 0

3 years ago

Water at a gauge pressure of 3.8 atm at street level flows into an office building at a speed of 0.68 m/s through a pipe 5.4 cm

Nataliya [291]

kxubj ysufuxtfuvhxub

7 0

3 years ago