Answer:
77.96dB
Explanation:
Recall that decibels are a unit of measuring intensity of sound, and depend on the logarithm of the intensity
the intensity, measured in decibels is given by:
I(db)=10log(I/I0)
I is the intensity in MKS units; I0 is the threshold intensity for human hearing (10^-12 W/m^2)
Thus, if the two sounds together have a dB of 81, we know:
81=10log(I/I0)
using the data above, we can find the intensity of the two sounds to be
0.000125 W/m^2
therefore, one firecracker has an intensity half of that, or 0.0000625W/m^2
now use this value to find the dB of one firecracker:
I(dB0=10log(0.0000625/10^-12)=77.96dB
Answer:
#_time = 7.5 10⁴ s
Explanation:
In order for the astronaut to be younger than the people on earth, it follows that the speed of light has a constant speed in vacuum (c = 3 108 m / s), therefore with the expressions of special relativity we have.
t =
where t_p is the person's own time in an immobile reference frame,

let's calculate
we assume that the speed of the space station is constant
t_ = 0.99998666657 s
therefore the time change is
Δt = t - t_p
Δt = 1 - 0.9998666657
Δt = 1.3333 10⁻⁵ s
this is the delay in each second, therefore we can use a direct rule of proportions. If Δt was delayed every second, how much second (#_time) is needed for a total delay of Δt = 1 s
#_time = 1 / Δt
#_time =
#_time = 7.5 10⁴ s
Electrons is the part of the atom that creats a magnetic feild
Answer:
Due to suffocation and toxic paint.
Explanation:
The population of hermit crabs has been decreasing because of suffocation and poison. Many crabs actually die slowly from suffocation because their gills require high humidity in order to breathe properly. Hermit crabs are slowly poisoned by tap water in which the toxic substances present in the paint that dissolves their shells that leads to the death of hermit crabs.
Answer:
Part a)

Part b)

Explanation:
As the uniform sphere is rolling down the inclined plane then the net force on the sphere is given as

also we have torque equation on it

for pure rolling


now we have

now we have


now given that

so we have



Part b)
If the inclined plane is frictionless then the acceleration is given as


