Answer:
Explanation:
The rate at which heat will be radiated is given by the expression
E = e Aσ ( T⁴ - T₀⁴ )
E is heat radiated , e is emissivity , A is area of surface , σ is stephan's constant T is temperature of the object and T₀ is temperature of the surrounding .
For all the objects given , e , σ T and T₀ are same so E will solely dependent on area of the surface
surface area of cube= 6 r² ,
surface area of sphere = 4 π r²
= 12.56 r²
hemisphere = 2 π r²
= 6.28 r²
12.56 r² >6.28 r² > 6 r²
heat radiated by sphere > heat radiated by hemisphere > heat radiated by cube .
"Apparent magnitude" means how bright a star looks to
a person on Earth.
-- The star that appears brightest is the one with the
lowest-number apparent magnitude . . . Star-C, at -4 .
-- All of them are visible from Earth, but may require some 'help'.
The dimmest stars visible with good human eyes under dark,
non-polluted skies are those with apparent magnitude around 6.
Stars B and C would be visible to the unaided eye, but Star-A
would require binoculars.
Around here, a few miles outside of the Chicago city limits, we're
lucky to see Magnitude-4 without binoculars.
-- It's not possible to determine which star has the highest luminosity.
The apparent magnitude depends on the star's distance from Earth
as well as its luminosity.
A flashlight 3 feet from your face appears much brighter than any
star, although any star is more luminous than the flashlight.
Distance from you has a lot to do with it.
_____________________________________________
"Absolute magnitude" means how bright each star would appear
to a person on Earth if all stars were at the same distance from us.
(The distance happens to be 32.6 light years.) It only depends on
the star's real luminosity, not on its distance.
-- It's not possible to determine which star appears brightest.
Star-C (absolute -7) would appear brightest if all stars were
equal distances from us. But a flashlight ... which has a huge-
number absolute magnitude because we couldn't see at all from
32.6 light years away ... can appear very bright from 3 feet in
front of your face.
-- They're all visible from Earth, but a star with absolute magnitude
greater than 6 would need binoculars (or better) to be visible.
-- Yes, if you know a star's absolute magnitude, then you know its
luminosity. The lowest-number absolute magnitudes are the ones
that would appear brightest if all stars were the same distance from
us, so they're the stars with the greatest luminosity. From this group,
that's Star-C.
Answer:
<h2>
The magnitude of force F is 18N</h2>
Explanation:
The magnitude of the force in the set up can be solved for using the principle of moment. According to the principle, the sum of clockwise moment is equal to the sum of anticlockwise moments.
Moment = Force * perpendicular distance
Clockwise moments;
The force that acts clockwise is the unknown Force F and 4N force. If the beam rests on a pivot 60 cm from end X and a Force F acts on the beam 80 cm from end X, the perpendicular distance of the force F from the pivot is 80-60 = 20cm and the perpendicular distance of the 4N force from the pivot is 60-50 = 10cm
Moment of force F about the pivot = F * 20
Moment of 4N force about the pivot = 4*10 = 40Nm
Sum of clockwise moment = 40+20F...(1)
Anticlockwise moment;
The 8N will act anticlockwisely about the pivot.
The distance between the 8N force and the pivot is 60-10 = 50cm
Moment of the 8N force = 8*50
=400Nm...(1)
Equating 1 and 2 we have;
40+20F = 400
20F = 400-40
20F = 360
F = 18N
The magnitude of force F is 18N
Answer:
a) Calcule a frequência em RPM
= 0.6 RPM
b) a velocidade escalar do carro em m/s.
= 20m/s
Explanation:
a) Calcule a frequência em RPM
A fórmula para calcular a frequência é: 1/T
onde T= Tempo (seconds)
T = 100s
A frequência = 1/100s
A frequência = 0.01Hz
em RPM
A fórmula para calcular a frequência em RPM =
1 Hz = 60RPM
0.01Hz =
A frequência em RPM = 0.01Hz × 60
= 0.6 RPM
b) a velocidade escalar do carro em m/s.
A fórmula para calcular a velocidade escalar = diâmetro ou distância (m) ÷ tempo (s)
Diâmetro ou Distância = 2.0km
Converter 2.0km para m
1 km = 1000m
2km =
2 km × 1000m
= 2000m
A velocidade escalar = 2000m ÷ 100s
A velocidade escalar = 20m/s
Answer:
a) Frequency in RPM
= 0.6 RPM
b) Scalar Velocity
= 20m/s
Explanation:
a) Frequently in RPM
Formula : 1/T
Where T= Time (seconds)
T = 100s
= 1/100s
= 0.01Hz
Frequency in RPM =
1 Hz = 60RPM
0.01Hz = 0.01Hz × 60
= 0.6 RPM
b) Scalar velocity
The formula = Diameter or Distance ÷ Time
Diameter or Distance = 2.0km
Convert 2.0km to m
1 km = 1000m
2km =
2 km × 1000m
= 2000m
Scalar Velocity = 2000m ÷ 100s
Scalar Velocity = 20m/s