"<em>F = dP/dt. </em> The net force acting on an object is equal to the rate at which its momentum changes."
These days, we break up "the rate at which momentum changes" into its units, and then re-combine them in a slightly different way. So the way WE express and use the 2nd law of motion is
"<em>F = m·A.</em> The net force on an object is equal to the product of the object's mass and its acceleration."
The two statements say exactly the same thing. You can take either one and work out the other one from it, just by working with the units.
1)a 2)D 3)a. I think the answers are
A black hole is a cosmological object that is created when a massive star comes to the end of its life and collapses under its own gravity. Black holes have massive gravitational fields that even light cannot escape beyond a certain distance. Before being engulfed, matter that is pulled into a black hole should become very hot and emit electromagnetic radiation.
Answer: When a liquid or gas is heated, the molecules move faster, bump into each other, and spread apart. Because the molecules are spread apart, they take up more space. ... The molecules move more slowly and take up less space. Therefore temperature can affect density.
Explanation:
Let the height where we are trapped is H
now to find the time to reach the key at the bottom is given as
now we have
now if the speed of sound is considered to be 340 m/s then time taken by the sound to reach at the top is given as
now the total time is given as
now by solving above equation we have
H = 48 m
now height of one floor is 3 m
so our position must be
