An object of mass 5 kilograms is moving across a surface in a straight line with a speed of 3.5 meters/second. What amount of force would be required to keep the object in motion if you ignore the surface friction?
A 0 newtons
B 175 newtons
C 35 newtons
D 5 newtons

Explain the doppler effect in terms of frequency, wavelength, and speed.

Ineed the answer to question 1 , i’m desperate

This is important 1. what happens to the speed of molecules in water vapor when it condenses to form a liquid? (2 points) the molecules slow down. the molecules speed up. the molecules slow down and then speed up. the molecules speed up and then slow down. 2. how might human activities change to compensate for a decrease in water supplies? (2 points) humans might build a factory. humans might build drainage systems. humans might extract more water from the ground. human behavior does not change because of the water cycle. i'll be grateful if anyone can answer these 2 questions !