Answer:
0.04kg
Explanation:
Explanation in pics:
The formula for kinetic energy is KE = 1/2mv². So now the question asks for the mass, not KE. So we need to rearrange the formula so that we are calculating the mass. So, the formula for mass is m=KE/(1/2v²). Now we just substitute the values into the formula. Then just follow what it shows in the pic
Answer:
.
Explanation:
The frequency 
of a wave is equal to the number of wave cycles that go through a point on its path in unit time (where "unit time" is typically equal to one second.)
The wave in this question travels at a speed of 
. In other words, the wave would have traveled 
in each second. Consider a point on the path of this wave. If a peak was initially at that point, in one second that peak would be
How many wave cycles can fit into that ? The wavelength of this wave
gives the length of one wave cycle. Therefore:
.
That is: there are 
wave cycles in of this wave.
On the other hand, Because that of this wave goes through that point in each second, that wave cycles will go through that point in the same amount of time. Hence, the frequency of this wave would be
Because one wave cycle per second is equivalent to one Hertz, the frequency of this wave can be written as:
.
The calculations above can be expressed with the formula:
,
where
represents the speed of this wave, and 
represents the wavelength of this wave.
Mg magnesium becuase one period down and one group to the side
Answer:
I₁ =1250 kg.m²
Explanation:
Given that
Angular speed of Merry ,ω₁= 0.2 rad/s
Angular speed of technician ,ω₂= 0.04 rad/s
Moment of the inertia of the technician ,I₂= 5000 kg.m²
Lets assume that
Moment of the inertia of merry with respected to the ground=I₁
There is no any external torque ,that is why angular momentum of the system will be conserve.
Now by conserving angular momentum
I₁ ω₁=(I₁+I₂)ω₂
I₁ x 0.2 = (I₁ +5000 ) x 0.04
I₁ (0.2-0.04) = 5000 x 0.04
I₁ =1250 kg.m²
