Answer:
v = wavelength * frequency
frequency = 5200 m/s / .2 m = 26000 / sec
20,000 / sec is optimistic for the upper frequency of human hearing
So 26,000 is above the hearing range for human ears
Answer:
The climate of the earth throughout history has always been <em><u>fluctuated between hot and cold periods. </u></em>
gravitational potential is directly proportional to the height of the object relative to a reference line and is given as
PE = mgh
where m = mass of object , g = acceleration due to
gravity and h = height of the object above the reference line .
as the skydiver falls , its height above the ground decrease and hence the gravitational potential energy of the skydiver decrease.
as per conservation of energy , total energy of the skydiver must remain constant all the time . hence the decrease in potential energy appears as increase in kinetic energy by same amount to keep the total energy constant
KE + PE = Total energy
so as the skydiver falls , it gains speed and hence the kinetic energy of skydiver increase since kinetic energy is directly proportional to the square of the speed.
when the parachute opens, the skydiver experience force in upward which tries to balance the weight of the skydiver. hence the speed of the skydiver decrease until upward force becomes equal to the downward force. hence the kinetic energy decrease just after the parachute opens
Hi,
The correct answer is letter B.
The last group contains noble gases, while both along the top and along the bottom the elements on the right are non-metals.
I think that it is true, but I'm not exactly sure. :)
