Answer:
<em>The velocity of the ball as it hit the ground = 19.799 m/s</em>
Explanation:
Velocity: Velocity of a body can be defined as the rate of change of displacement of the body. The S.I unit of velocity is m/s. velocity is expressed in one of newtons equation of motion, and is given below.
v² = u² + 2gs.......................... Equation 1
Where v = the final velocity of the ball, g = acceleration due to gravity, s = the height of the ball
<em>Given: s = 20 m, u = 0 m/s</em>
<em>Constant: g = 9.8 m/s²</em>
<em>Substituting these values into equation 1,</em>
<em>v² = 0 + 2×9.8×20</em>
<em>v² = 392</em>
<em>v = √392</em>
<em>v = 19.799 m/s.</em>
<em>Therefore the velocity of the ball as it hit the ground = 19.799 m/s</em>
Answer:1.55 times
Explanation:
Given
First wavelength
Second wavelength
According wien's diplacement law
where 
T=Temperature
Let 
be the temperatures corresponding to 
respectively.
Thus object with 
is 1.55 times hotter than object with wavelength 
The silver coating on the inner bottle prevents heat transfer by radiation, and the vacuum between its double wall prevents heat moving by convection. The thinness of the glass walls stops heat entering or leaving the flask by conduction.
