Lực hút trái đất gọi Là trọng lực
Answer:
L = L0 (1 + c T) where c is the coefficient and T the change in temperature
L = 50 ( 1 + 2.05E-6 * 50) = 50.0051 cm
Answer:
The force will be zero
Explanation:
Due to the symmetric location of the +2μC charges the forces the excert over the +5μC charge will cancel each other resulting in a net force with a magnitude of zero.However in this case it would be an unstable equilibrium, very vulnerable to a kind of bucking. If the central charge is not perfectly centered on the vertical axis the forces will have components in that axis that will add together instead of canceling each other.
Answer:
Explanation:
In case of oil slick a thin layer of oil is formed on water . This thin layer creates a rainbow of colour . The phenomenon is due to interference of light waves , one reflected from the upper surface of oil and the other reflected from the lower surface of the oil.
For formation of bright colour
2 μ t = ( 2n + 1 ) λ / 2
μ is refractive index of oil , t is thickness of oil layer λ is wave length of light falling on the layer .
given μ = 1.2 , λ = 750 x 10⁻⁹ ,
2 x 1.2 t = ( 2n + 1 ) 750 x 10⁻⁹ / 2
For minimum thickness n = 0
2.4 t = 375 x 10⁻⁹
t = 156.25 n m
B ) If the refractive index of layer of medium below oil is less than that of oil , the condition of formation of colour changes
The new condition is
2 μ t = n λ
2 x 1.5 t = 750 nm , n = 1 for minimum wavelength .
t = 250 nm
C ) Light mostly transmitted means dark spot is formed at that point .
For that to be observed from water side , the condition is
2 μ t = ( 2n + 1 ) λ / 2
λ = 4μ t / ( 2n + 1 )
For maximum wavelength n = 0
λ = 4μ t
= 4 x 1.5 x 200 nm
= 1200 nm .
We have the equation of motion 
, where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.
Here s = 300 m, u = 0 m/s, a = 9.81 
Substituting
Now we have v = u+at, where v is the final velocity
Here u = 0 m/s, a= 9.81 and t = 7.82 seconds
Substituting
v = 0+9.8*7.82 = 76.68 m/s
The speed with which the penny strikes the ground = 76.68 m/s.
