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3 years ago

Gold is used to make a super thin layer on the visors of astronauts' helmets because of which property in particular?

Physics

2 answers:

Radda [10]3 years ago

8 0

C gold is the best material for reflecting heat which is needed in space.

8090 [49]3 years ago

7 0

B, because gold is the most malleable substance of all.

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ValentinkaMS [17]

Hi there!

We know that:

U (Potential energy) = mgh

We are given the potential energy, so we can rearrange to solve for h (height):

U/mg = h

g = 9.81 m/s²

m = 30 g ⇒ 0.03 kg

0.062/(0.03 · 9.81) = 0.211 m

8 0

3 years ago

25 POINTS ------------------ (usatestprep)

Airida [17]

Answer:

D) The heavier ball will have a higher temperature because the change of temperature is inversely proportional to mass.

Explanation:

As stated in the problem, the amount of heat released by each ball is

$Q=mC_p \Delta T$

where

m is the mass of the ball

Cp is the specific heat of iron (so, it is equal for both balls)

$\Delta T$ is the change in temperature of each ball

In this problem, we are said that the amount of heat released by the two balls, Q, is the same. Cp is also the same: this means that the product $m\Delta T$ must be the same for the two balls. So, the mass and the change in temperature are inversely proportional: therefore, the heavier ball will have a smaller change in temperature. And since both balls starts from the same temperature, 100 C, this means that the heavier ball will reach a higher temperature than the lighter ball.

6 0

3 years ago

You run a race with your friend. At first you each have the same kinetic energy, but then you find that she is beating you. When

Blizzard [7]

Answer:

52.49 Kg

Explanation:

Let m1 and v1 denote your mass and velocity respectively

Let m2 and v2 denote your friends mass and velocity respectively

Kinetic energy is given by

$KE= 0.5mv^{2}$

Since your kinetic energies are the same hence

$0.5m1(v1)^{2}=0.5m2(v2)^{2}$

$m1(v1)^{2}=m2(v2)^{2}$ and making m2 the subject then

$m2=\frac { m1(v1)^{2}}{(v2)^{2}}$

Since v2 is v1+0.28v1=1.28v1

Substituting m1 for 86 Kg

$m2=\frac { 86 Kg(v1)^{2}}{(1.28v1)^{2}}= 52.49023\approx 52.49 Kg$

3 0

3 years ago

If the temperature of the conductor is increased, the electrons’ speeds decrease

Tatiana [17]

Answer:

HOPE IT HELPS YOU!!!

Explanation:

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5 0

3 years ago

A square coil ℓ = 2cm on a side with 30 turns rotates in a uniform magnetic field, B~ = B0zˆ = 0.1Tˆz, such that the normal of t

kow [346]

Answer:

a) 1.2*10^{-3}cos(1.25t)

b) 0.49mV

Explanation:

a) The coil rotates periodically with period T. Hence, we can write the variation of the magnetic flux with a sinusoidal function, and with max flux NAB. Thus, we have that:

$\Phi_B(t)=NABcos(\omega t)\\\\\omega=\frac{2\pi}{T}=1.25\frac{rad}{s}\\\\A=l^2=(0.02m)^2=4*10^{-4}m^2\\\\B=0.1T\\\\\Phi_B(t)=1.2*10^{-3}cos(1.25 t) W$

where we have used the values given by the information of the problem for N B and A.

the emf is given by:

$emf=-\frac{d\Phi_B}{dt}=-NBA\omega sin(\omega t)\\\\emf(t=12.5s)=-(30)(0.1T)(4*10^{-4})(1.25\frac{rad}{s})sin(1.25*12.5)=1.49*10^{-4}V=0.49mV$

hope this helps!!

5 0

3 years ago