On a cold day (0C) you observe a person far away from you hit a piece of metal with a hammer. Then 0.75 seconds later you hear the sound of the hammer hitting the metal. How far are you from the other person?

248.48 meters

Explanation:

When there is low temperature than the normal room temperature, the speed of sound in air decreases because at lower temperatures the movement of air molecules through which the sound travels gets decreases.

Speed of sound at 0⁰ is found to be approximately 331.3 m/s.

The question says that sound was heard by the observer 0.75 seconds later after hammer hit the metal.

As we know, Distance traveled = Speed × Time taken

So, distance traveled by sound in 0.75 seconds = 331.3 × 0.75 = 248.48 m

So, the observer was standing 248.48 meters away from the other person hitting the hammer.

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.

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.