The intensity level from a set of quintuplets (five babies) : <u>56 dB</u>
<h3>Further explanation</h3>Wave intensity is the power of a wave that is moved through a plane of one unit that is perpendicular to the direction of the wave
Can be formulated
I = intensity, W m⁻²
P = power, watt
A = area, m²
The farther the distance from the sound source, the smaller the intensity
So the intensity is inversely proportional to the square of the distance from the source
Intensity level (LI) can be formulated
Io = 10⁻¹²
For the level of intensity of several sound sources as many as n pieces can be formulated:
<h3>LIn = LI1 + 10 log n </h3>
The intensity level of 1 baby is
LI = 10 log 8.10⁴
LI = 49
The intensity level of 5 babies :
LI5 = LI + 10 log n
LI5 = 49 + 10 log 5
LI5 = 49 + 7
LI5 = 56
<h3>Learn more</h3>The intensity of a laser beam
electric field
magnetism
The speed of the ball is 101miles/hr.
A mile is a unit of length that is exactly 1,609.344 metres long. Similarly, 5,280 feet or 1,760 yards make up one mile. The mile is an imperial and common US measurement of distance.
We just have to deal with unit conversions.
One mile is 5280 feet, or 1 ft = 0.000189
The speed of the ball in miles per hour is
So, the speed of the ball in miles per hour is 101miles/hr.
Learn more about miles here;
#SPJ4
3) The work done is D. zero
4) The kinetic energy is B. 180 J
5) The potential energy is A. 120 J
6) The work done depends on B. position
7) The example of non-renewable energy is C. coal
8) The power expended is
9) The efficiency is A. 100%
10) The velocity ratio is 5
Explanation:
3)
The work done by a force acting an object is given by:
where :
F is the magnitude of the force
d is the displacement
is the angle between the direction of the force and the displacement
When the force is applied perpendicular to the direction of motion,
Therefore, the work done is:
4)
The kinetic energy of a body is given by
where
m is the mass of the body
v is its speed
For the girl in this problem, we have
m = 40 kg
v = 3 m/s
Therefore her kinetic energy is
5)
The potential energy of an object is given by
where
m is the mass
is the acceleration of gravity
h is the heigth of the object relative to the ground
For the ball in this problem,
m = 0.4 kg
h = 30 m
So, the potential energy is
6)
A conservative field is a field for which the work done by the field on an object does not depend on the path taken, but only on the initial and final position of the object.
Gravitational and electric fields are examples of conservative fields. In fact:
For any conservative field, it is possible to define a "potential" function, which represents the energy per unit mass/charge, and depends only on the position of the object.
7.
Therefore, the example of non-renewable energy in this case is
C. Coal
8.
For an object pushed by a force F and moving at a constant velocity v, the power expended is given by
where F is the force and v is the velocity.
for the rocket in this problem, we have:
F = 10 N is the force propelling the rocket
v = 3000 m/s is its velocity
Substituting into the equation, we find the power expended:
9.
The efficiency of a machine is given by
where
is the energy in input to the machine
is the useful work in output from the machine
For a real machine, the useful work in output is always lower than the energy input, because part of the energy is "wasted" and converted into thermal energy due to the presence of internal frictions. However, for an ideal machine, all the input energy is converted into useful work, so
And therefore the efficiency is
which means 100%.
10.
The velocity ratio of a block and tackle system is the ratio between the distance moved by the effort and the distance moved by the load.
In a block and tackle system, the velocity ratio is also equal to the number of pulleys in the system.
For the system in the problem, there are 5 pulleys: therefore, this means that when the effort moves 5 metres, the load moves 1 metres, therefore the velocity ratio is
Learn more about kinetic and potential energy:
#LearnwithBrainly