PLZ HELP I DON'T UNDERSTAND!! a boy is playing catch with his friend. He throws the ball straight up. When it leaves his hand, t
1 answer:
Explanation:
The mass of a ball, m = 2 kg
It is traveling with a speed of 10 m/s
The ball's kinetic energy just as it leaves the boy's hand is calculated as follows :
The ball's kinetic energy just as it leaves the boy's hand is 100 J. The potential energy of the ball when it reaches the highest point is same as the kinetic energy as it leaves the boy's hand.
Hence, the required kinetic and potential energy is 100 J.
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Answer:
Explanation:
Part A) Using
light intensity I= P/A
A= Area= π (Radius)^2= π((0.67*10^-6m)/(2))^2= 1.12*10^-13 m^2
Radius= Diameter/2
P= power= 10*10^-3=0.01 W
light intensity I= 0.01/(1.12*10^-13)= 9*10^10 W/m^2
Part B) Using
I=c*ε*E^2/2
rearrange to solve for E= ((I*2)/(c*ε))
c is the speed of light which is 3*10^8 m/s^2
ε=permittivity of free space or dielectric constant= 8.85* 10^-12 F⋅m−1
I= the already solved light intensity= 8.85*10^10 W/m^2
amplitude of the electric field E= (9*10^10 W/m^2)*(2) / (3*10^8 m/s^2)*(8.85* 10^-12 F⋅m−1)
---> E= (1.8*10^11) / (2.66*10^-3) =
(6.8*10^13) = 8.25*10^6 V/m
The kinetic energy gained by the air molecules is 0.0437 J
<h3 />Given:
Mass of a coffee filter, m = 1.5 g
Height from which it is dropped, h = 3 m
Speed at ground, v = 0.7 m/s
Initially, the coffee filter has potential energy. It is given by :
P = 1.5 × 10⁻³ kg × 9.8 m/s² × 3m
P = 0.0441 J
Finally, it will have kinetic energy. It is given by :
×
× 10⁻³ × (0.7)²
E = 0.000343 J
The kinetic energy Kair did the air molecules gain from the falling coffee filter is :
E = 0.000343 - 0.0441
= 0.0437 J
So, the kinetic energy Kair did the air molecules gain from the falling coffee filter is 0.0437 J
Learn more about kinetic energy here:
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