Answer: 63 m/s
Explanation: If wheel drops vertically, you can use
conservation of energy : Ep = Ek. mgh = ½mv^2 and
solve v = √(2gh ) = √ (2·9.81 m/s²·200 m) = 62.6 m/s.
NOTE: wheel has also horizontal speed which was not mentioned here.
Before solving this question first we have to understand work function.
The work function of a metal is amount of minimum energy required to emit an electron from the surface barrier of metal . Whenever the metal will be exposed to radiation a part of its energy will be utilized to emit an electron while rest will provide kinetic energy to the electron.
Let f is the frequency of incident radiation and f' is the frequency corresponding to work function. Let v is the velocity of the ejected electron.
we know that velocity of an electromagnetic wave is the product of frequency and wavelength. Hence frequency f is given as-
![f=\frac{c}{\lambda}](https://tex.z-dn.net/?f=f%3D%5Cfrac%7Bc%7D%7B%5Clambda%7D)
where c is velocity of light and
is the wavelength of the wave.
As per the question incident wavelength =313 nm
[as 1 nm =10^-9 m]
The wavelength corresponding to work function is 351 nm i.e
![351*10^{-9} m](https://tex.z-dn.net/?f=351%2A10%5E%7B-9%7D%20m)
we know that hf=hf'+K.E [ h is the planck's constant whose value is 6.63×10^-34 J-s]
⇒K.E =hf-hf'
![\frac{1}{2} mv^2=hf-hf'](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7D%20mv%5E2%3Dhf-hf%27)
![v^2=\frac{2}{m} [hf-hf']](https://tex.z-dn.net/?f=v%5E2%3D%5Cfrac%7B2%7D%7Bm%7D%20%5Bhf-hf%27%5D)
![v^2=\frac{2}{m} [\frac{hc}{\lambda} -\frac{hc}{\lambda ' }]](https://tex.z-dn.net/?f=v%5E2%3D%5Cfrac%7B2%7D%7Bm%7D%20%5B%5Cfrac%7Bhc%7D%7B%5Clambda%7D%20-%5Cfrac%7Bhc%7D%7B%5Clambda%20%27%20%7D%5D)
![=\frac{2}{9.1*10^{-31}kg } *{6.63*10^{-34} Js *3*10^{8} [\frac{1}{313*10^{-9} } -\frac{1}{351*10^{-9} } ]](https://tex.z-dn.net/?f=%3D%5Cfrac%7B2%7D%7B9.1%2A10%5E%7B-31%7Dkg%20%7D%20%2A%7B6.63%2A10%5E%7B-34%7D%20Js%20%2A3%2A10%5E%7B8%7D%20%5B%5Cfrac%7B1%7D%7B313%2A10%5E%7B-9%7D%20%7D%20-%5Cfrac%7B1%7D%7B351%2A10%5E%7B-9%7D%20%7D%20%5D)
![=0.001512021301356*10^{14} m^2/s^2](https://tex.z-dn.net/?f=%3D0.001512021301356%2A10%5E%7B14%7D%20m%5E2%2Fs%5E2)
![v=\sqrt{0.0015120241301356*10^{14} } m/s](https://tex.z-dn.net/?f=v%3D%5Csqrt%7B0.0015120241301356%2A10%5E%7B14%7D%20%7D%20m%2Fs)
![=0.3888476161313*10^{7} m/s](https://tex.z-dn.net/?f=%3D0.3888476161313%2A10%5E%7B7%7D%20m%2Fs)
[ans]
Answer:
Atherosclerosis is a disease of the arteries characterized by the deposition of plaques of fatty material on the inner walls.
Explanation:
Atherosclerosis often has no symptoms until a plaque ruptures or the buildup is severe enough to block blood flow.
Answer:
Option C
Explanation:
given,
velocity of airplane = 80 m/s
angle with the horizontal = 15°
speed of the ground= ?
when the plane is taking off the horizontal component of the velocity is v cosθ
so,
ground speed of the airplane is = ![v\times cos\theta](https://tex.z-dn.net/?f=v%5Ctimes%20cos%5Ctheta)
=
v = 77.27 m/s
horizontal velocity of the air plane comes out to be 77.27 m/s ≅ 77 m/s
so, the correct option is Option C