The Sun's chemical composition was about 70%% hydrogen when it formed, and about 13%% of this hydrogen was available for eventual fusion in the core. (The rest remains in layers of the Sun where the temperature is currently too low for fusion.)Use the given data to calculate the total mass of hydrogen available for fusion over the lifetime of the Sun.

1.8 × 10^29 kg

Explanation:

The computation of the total mass is shown below;

As we know that

The total mass of the sun is

= 2 × 10^30 kg

Since 70% of the mass involves hydrogen gas, so total mass of the hydrogen gas is

= 70% × 2 × 10^30 kg

= 1.4 × 10^30 kg

And, 13% available for fusion, so the hydrogen gas mass is

= 13% × 1.4 × 10^30 kg

= 1.8 × 10^29 kg

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me