a low-flying jet aircraft approaches a stationary Observer on the ground at the speed of 1000 km / HR on a day when the speed of sound is 345 m / s. A. If the engine emits a sound of frequency 4000 HZ what frequency does the stationary observer receive as the plane approaches? And as the plane flies away?​

i guess it’s a and b

scientific laws are the result of testing theories and proving them to be facts.

which piece of furniture will have the most inertia and give the furniture movers the most difficulty in moving?  

answer

a 75kg dining table

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.