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4 years ago

When the heart beats faster, blood vessels need to _____ more. open close move

Physics

2 answers:

Yuki888 [10]4 years ago

6 0

I'm pretty sure it is open more

snow_tiger [21]4 years ago

4 0

vessels need to open more.

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This structure shows how atoms make up sugar. The different colors represent different types of atoms. Is sugar an element, just

Romashka-Z-Leto [24]

Sugar is a compound

4 0

3 years ago

Read 2 more answers

A circular saw blade with radius 0.175 m starts from rest and turns in a vertical plane with a constant angular acceleration of

ANEK [815]

Answer:

The distance the piece travel in horizontally axis is

L=3.55m

Explanation:

$a=2 \frac{rev}{s^{2}} \\h=0.820m\\r = 0.125 m
\\d=150rev$

$d= 155 rev = 155(2\pi ) = 310\pi rad$

$a= 2.0 \frac{rev}{s^{2} } = 2.0(2\pi ) = 4.0\pi \frac{rev}{s^{2} }$

$d=d_{i}+vo*t+\frac{1}{2}*a*t^{2} \\ di=0\\vo=0\\d=\frac{1}{2}*a*t^{2}\\t=\sqrt{\frac{2*d}{a}}\\t=\sqrt{\frac{2*310 rad}{4\frac{rad}{s^{2}}}} \\t=12.449$

$w=a*t\\w=4\frac{rad}{s^{2}}*12.449s\\ w=49.79 \frac{rad}{s}$

Now the angular velocity is the blade speed so:

$V=w*r\\V=49.79 \frac{rad}{s}*0.175m\\V=8.7 \frac{m}{s}$

assuming no air friction effects affect blade piece:

time for blade piece to fall to floor

$t=\sqrt{\frac{2*h}{g}}\\t=\sqrt{\frac{2*0.820m}{9.8\frac{m}{s^{2} } }}\\t=0.409s$

Now is the same time the piece travel horizontally

$L=t*V\\L=0.409s*8.7\frac{m}{s}\\L=3.55m$

blade piece travels HORIZONTALLY = (24.5)(0.397) = 9.73 m ANS

6 0

4 years ago

The wavelengths of light emitted by a firefly span the visible spectrum but have maximum intensity near 550 nm. A typical flash

Reil [10]

Answer:

$3.3\cdot 10^{15}$

Explanation:

First of all, let's calculate the energy of a single photon of wavelength

$\lambda=550 nm=5.5\cdot 10^{-7}m$

which is given by

$E_1 = \frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34}Js)(3\cdot 10^8 m/s)}{5.5\cdot 10^{-7} m}=3.6\cdot 10^{-19} J$

The power of the flash is

$P=1.2 mW=0.0012 W$

and the time it lasts is

$t=100 ms=0.1 s$

so the total energy delivered in one flash is

$E=Pt=(0.0012 W)(0.1 s)=1.2\cdot 10^{-3}J$

This energy contains exactly N photons each of energy $E_1$ , so the number of photons emitted in one flash is

$N=\frac{E}{E_1}=\frac{1.2\cdot 10^{-3} W}{3.6\cdot 10^{-19}J}=3.3\cdot 10^{15}$

3 0

3 years ago

You overindulged on a delicious dessert, so you plan to work off the extra calories at the gym. To accomplish this, you decide t

iragen [17]

Answer:

17086

Explanation:

We are given that

Weight=5 kg

Distance of elbow from the weight=d=35 cm= $\frac{35}{100}=0.35 m$

1 m=100 cm

g= $9.8m/s^2$

Work done each time on the weight= $mgh=5\times 9.8\times 0.35=17.15 J$

20% means 0.20 of food energy=Work done each time on weight

Total work done in each time= $\frac{17.15}{0.2}=85.75J$

1 food calorie=4186 J

350 food calories= $350\times 4186 J$

Number of lift needed= $\frac{350\times 4186}{85.75}=17086$

Hence, you must do 17086 arm raises to work off 350 food calories.

6 0

3 years ago

Polystyrene has dielectric constant 2.6 and dielectric strength 2.0 ×× 10^7 V/m. A piece of polystyrene is used as a dielectric

LenKa [72]

Answer:

(a) 1133J/m

(b) 5.714m²

Explanation:

(a) u = 1/2×εE²

εo = 8.85×10-¹² F/m

E = 0.8 × 2.0×10⁷V/m = 1.6×10⁷V/m

u = 1/2×8.85×10-¹² × (1.6×10⁷)²= 1132.8J/m

(b)

U = 1/2CV² = 1/2(Aεo/d)×V²

U = 1/2(Aεo/d)×V²

U = 200mJ = 200×10-³

d = V/E = 500/ (1.6×10⁷) =3.13×10-⁵m

200×10-³ = 0.5×A×8.85×10-¹²×500²/3.13×10-⁵

200×10-³ = 0.035A

A = 200×10-³/ 0.035 = 5.714m².

8 0

3 years ago