Nuclear fusion and gravitational contraction
<span>constituent of star is hydrogen(including isotope) or helium. nuclear fission is almost impossible. D(deuterium; isotope of hydrogen) and T(tritium; also isotope of hydrogen) reacts and helium is formed. During this reaction, severe energy is generated. Heavier elements are formed and pulls each other. Gathered elements forms core of star. Gravity of the core prevents the gas to run away.</span>
<span>Balloons are blown up, and then rubbed against your shirt many times. The balloon then touches the ceiling. When released, the balloon remains stuck to the ceiling. The balloon is charged by contact. The ceiling has a neutral charge. The charged balloon induces a slight surface charge on the ceiling opposite to the charge on the balloon. Balloon and ceiling electric charges are opposite in sign, so they will attract each other. Since both the balloon and the ceiling are insulators, charge can not flow from one to the other. The charge on the balloon is fixed on the balloon and the charge on the ceiling remains fixed to the ceiling. It just so happens that the<span> electrostatic force the ceiling exerts on the balloon is sufficient to hold the balloon in place (i.e. overcomes gravity, etc.).</span></span>
<h2>The option a is most appropriate </h2>
Explanation:
The total pressure due to liquid column at any place is the sum of
( i ) pressure due to liquid column called hydrostatic pressure
( ii ) the pressure due to air column above the liquid column , which is called the static pressure
Thus total pressure is the sum of hydrostatic and static pressure .
Thus the option a is most appropriate
The law of conservation of momentum tells us that momentum
is conserved, therefore total initial momentum should be equal to total final
momentum. In this case, we can expressed this mathematically as:
mA vA + mB vB = m v
where, m is the mass in kg, v is the velocity in m/s
since m is the total mass, m = mA + mB, we can write the
equation as:
mA vA + mB vB = (mA + mB) v
furthermore, car B was at a stop signal therefore vB = 0,
hence
mA vA + 0 = (mA + mB) v
1800 (vA) = (1800 + 1500) (7.1 m/s)
<span>vA = 13.02 m/s</span>
