Answer:
u = 449 m/s
Explanation:
Given,
Mass of the bullet, m = 26 g
Mass of the wooden block,M = 4.7 Kg
height of the block,h = 0.31 m
initial speed of the block, u = ?
Using conservation of energy




v = 2.47 m/s
Now, using conservation of momentum to calculate the speed of the bullet.
m u + M u' = (M+m)v
m u = (M+m)v
0.026 x u = (4.7+0.026) x 2.47
u = 449 m/s
Hence, the speed of the bullet is equal to 449 m/s.
Answer:
The answer is "
"
Explanation:
Z=2, so the equation is 
Calculate the value for E when:
n=2 and n=9
The energy is the difference in transformation, name the energy delta E Deduct these two energies
In this transition, the wavelength of the photon emitted is:



Answer:
Area of the rectangular field in kilometers is 0.09 
Explanation:
We know that 1 kilometers = 1000 meters
since we need to find the area in unit of kilometers
therefore converting length and width into kilometers
1000 meters = 1 kilometers
300 meters =
Likewise width = 0.3 km
Area = length x width
= 0.3km x 0.3 km
= 0.09 
The phenomenon which is responsible for this effect is called diffraction.
Diffraction is the ability of a wave to propagate when it meets an obstacle or a slit. When the wave encounters the obstacle or the slit, it 'bends' around it and it continues propagate beyond it. A classical example of this phenomenon is when a sound wave propagates through a wall where there is a small aperture (as in the example of this problem)