Answer:
B) The "lub-dub" sound originates from blood turbulence through the heart.
Explanation:
The systole and diastole in the heart produce the lub and dub sound in the heart.
The systole represents the contraction of both left and right ventricles and pumps the blood to the body and the right ventricle to the lungs. This involves the opening and closing of the valves. The closing of the atrioventricular valves produces lub sound.
At the end of the systole or ventricular contraction or when the blood has been pumped to the aorta and the pulmonary valves then the semilunar valves present in the aorta and pulmonary closes. This produces a sound dub.
Therefore,lub dub is associated with the physical contraction of the heart but not the turbulence of the blood.
Thus, the selected option is the correct answer.
Answer:
Since boron only has two electron shells, it is about as capable of gaining electrons as it is of losing electrons, so it behaves as a metalloid. The other elements in this group have more electron shells, so it is much easier for them to lose their valence electrons and they behave like metals.
We have a mass of 200g (0.2kg) moving at 20m/s
Kinetic Energy KE = ½ mv^2 where m is mass and v is velocity
Actually, v is a vector quantity, so KE = ½ mv•v
The dot product of 2 vectors a and b is abCosθ where θ is the angle between the vectors.
Obviously v•v = v^2 Cos0 = v^2
In this case, we have KE = ½ (0.2)(20^2) = 40kg-m^2/s^2 = 40J
So we have kinetic energy in the amount of 40 Joules.
Answer:
chloroplasts
Explanation:
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