Answer:
3099 J
Explanation:
The increase in thermal energy corresponds to the mechanical energy lost in the process.
The mechanical energy is given by the sum of gravitational potential energy and kinetic energy of the fireman:
At the top of the pole, the fireman has no kinetic energy, so all his mechanical energy is just potential energy:
When the fireman reaches the bottom, he has no gravitational potential energy, so his mechanical energy is just given by his kinetic energy:
So, the loss in mechanical energy was
and this corresponds to the increase in thermal energy.
Answer:
6.71×10⁻⁷ m
Explanation:
Using thin film constructive interference formula as:
<u>2×n×t = m×λ</u>
Where,
n is the refractive index of the refracted surface
t is the thickness of the surface
λ is the wavelength
If m =1
Then,
2×n×t = λ
Given that refractive index pf the oil is 1.22
Thickness of the oil = 275 nm
Also, 1 nm = 10⁻⁹ m
Thickness = 275×10⁻⁹ m
So,
Wavelength is :
<u>λ= 2×n×t = 2× 1.22 × 275×10⁻⁹ m = 6.71×10⁻⁷ m</u>
Answer:
Explanation:
Let hotter star has surface area of A . The cooler star would have surface area 9 times that of hotter star ie 9A , because its radius is 3 times hot star. Let temperature of hot star be T ₁.
Total radiant energy is same for both the star
Using Stefan's formula of black body radiation,
For cold star E = 9A x σ T⁴
For hot star E = A x σ T₁⁴
A x σ T₁⁴ = 9A x σ T⁴
T₁⁴ = (√3)⁴T⁴
T₁ = √3T .
b )
Let the peak intensity wavelength be λ₁ and λ₂ for cold and hot star .
As per wein's law
for cold star , λ₁ T = b ( constant )
for hot star λ₂ √3T = b
dividing
λ₁ T / λ₂ √3T = 1
λ₂ / λ₁ = 1 / √3
Answer:
Explanation:
The standard unit of momentum Is kgm/s
And momentum is the product of mass and velocity
Then,
Momentum = mass × velocity
P = mv
Where
m is mass in kg
v is velocity in m/s
Now,
Given that,
M = 31.8mg
1mg = 10^-3g
So, m = 31.8 × 10^-3g
Also, 1000g = 1kg → 1g = 10^-3 kg
So,
m = 31.8 × 10^-3 × 10^-3kg
m = 31.8 × 10^-6 kg
v = 2.53mi/hr
1mile = 1609.34 m
1 hour = 3600seconds
Then,
v = 2.53 × 1609.34m/ 3600s
v = 1.13 m/s
So, momentum is given as
P = mv
P = 31.8 × 10^-6 × 1.13
P = 3.597 × 10^-5 kgm/s
