Answer:
a) I = 1,894 10¹⁰ W / m², b) E = 1.376 10⁵ N / C
Explanation:
a) intensity is defined as energy per unit area per unit time
I = P / A
let's reduce the magnitudes to the SI system
P = 10 mW = 10 10⁻³ W
d = 0.82 μm = 0.82 10⁻⁶ m
the laser area is
A =π r² = π d²/4
A =π (0.82 10⁻⁶)²/4
A = 5.28 10⁻¹³ m²
we calculate
I =
I = 1,894 10¹⁰ W / m²
b) average intensity and electric field are related
I = E * E
E = √I
E =
E = 1.376 10⁵ N / C
Answer:
Work done, W = 1.44 kJ
Explanation:
Given that,
Mass of boy, m = 74 kg
Initial speed of boy, u = 1.6 m/s
The boy then drops through a height of 1.56 m
Final speed of boy, v = 8.5 m/s
To find,
Non-conservative work was done on the boy.
Solution,
The work done by the non conservative forces is equal to the sum of total change in kinetic energy and total change in potential energy.
W = 1447.21 Joules
or
W = 1.44 kJ
Therefore, the non conservative work done on the boy is 1.44 kJ.