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Misha Larkins [42]
3 years ago
9

Which radioactive isotopes did the Curies discover

Physics
2 answers:
Paraphin [41]3 years ago
5 0

the Curies discovered the existence of the elements radium and polonium in their research of pitchblende.

nadezda [96]3 years ago
3 0

Answer:

radium and polonium

Explanation:

Because I googled it.

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A 30 kg male emperor penguin under a clear sky in the Antarctic winter loses very little heat to the environment by convection;
yarga [219]

Answer:

Rate of energy loss by radiation is 28.31 Watt

Explanation:

Given that;

m = 30 kg

power p = 12 W

emissivity e = 0.97

Surface Area A = 0.56 m²

outside of the penguin's body  T = −22°C

surroundings Temperature Ts = -38°C

the rate of energy loss by radiation = ?

Now, using Stefan-Boltzmann law;

P = σeA [ T⁴ - Ts⁴ ]

Stefan's constant σ = 5.67 × 10⁻⁸

so we substitute

P = 5.67 × 10⁻⁸ × 0.97 ×  0.56  [ (-22 + 273 k)⁴ - (-38 + 273 k )⁴]

= 3.079944 × 10⁻⁸ [ 919325376]

=  28.31 Watt

the rate of energy loss by radiation is 28.31 Watt

8 0
3 years ago
A container has a 5m^3 volume capacity and weights 1500 N when empty and 47,000 N when filled with a liquid. What is the mass de
Helen [10]

Answer:

927.62 kg/m³ and 0.9275.

Explanation:

Density: This can be defined as the ratio of the mass of a body and its volume.

The S.I unit of density is kg/m³.

Mathematically, Density can be expressed as

D = m/v......................... Equation 1

Where D = density of the body, m = mass of the body,v = volume of the body

Also,

m = W/g.................... Equation 2

Where W = weight of the body, g = acceleration due to gravity.

Given: W = 47000 - 1500 = 45500 N, g = 9.81 m/s²

Substitute into equation 2,

m = 45500/9.81

m = 4638.12 kg.

Also given: v = 5 m³

Substitute into equation 1,

D = 4638.12/5

D = 927.62 kg/m³

Hence the mass density of the liquid = 927.62 kg/m³

Specific gravity: This is the ratio of the density of a body to the density pf water.

R.d  = D/D'................................ Equation 3

Where R.d = specific gravity, D = density of the liquid, D' = density of water.

Given: D = 927.62 kg/m³, D' = 1000 kg/m³

Substitute into equation 3

R.d = 927.52/1000

R.d = 0.9275.

Hence the specific gravity of the liquid = 0.9275.

6 0
3 years ago
Hey guys,I hope u r gonna answer this question fast,SI system is extended from of MKS system.Why? I will be waiting for the answ
DerKrebs [107]

Answer:

Because SI system has fundamental units of MKS System

6 0
3 years ago
Read 2 more answers
The mantle in the earths core continuously heat up and cool down using convection currents
o-na [289]
This statements is true
7 0
3 years ago
Read 2 more answers
A man hits a 50 grams golf ball such that it leaves the tee at an angle of 40o with the horizontal and strikes the ground at the
lukranit [14]

Answer:

Explanation:

Range of projectile R = 20 m

formula of range

R = u² sin2θ / g

u is initial velocity , θ is angle of projectile

putting the values

20 = u² sin2x 40 / 9.8

u² = 199

u = 14.10 m /s

At the initial point

vertical component of u

= u sin40 = 14.1 x sin 40

= 9.06 m/s

Horizontal component

= u cos 30

At the final point where the ball strikes the ground after falling , its speed remains the same as that in the beginning .

Horizontal component of velocity

u cos 30

Vertical component

= - u sin 30

= - 9.06 m /s

So its horizontal component remains unchanged .

change in vertical component = 9.06 - ( - 9.06 )

= 18.12 m /s

change in momentum

mass x change in velocity

= .050 x 18.12

= .906 N.s

Impulse = change in momentum

= .906 N.s .

3 0
4 years ago
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