Answer:
4.42 x 10⁷ W/m²
Explanation:
A = energy absorbed = 500 J
η = efficiency = 0.90
E = Total energy
Total energy is given as
E = A/η
E = 500/0.90
E = 555.55 J
t = time = 4.00 s
Power of the beam is given as
P = E /t
P = 555.55/4.00
P = 138.88 Watt
d = diameter of the circular spot = 2.00 mm = 2 x 10⁻³ m
Area of the circular spot is given as
A = (0.25) πd²
A = (0.25) (3.14) (2 x 10⁻³)²
A = 3.14 x 10⁻⁶ m²
Intensity of the beam is given as
I = P /A
I = 138.88 / (3.14 x 10⁻⁶)
I = 4.42 x 10⁷ W/m²
Let the key is free falling, therefore from equation of motion
.
Take initial velocity, u=0, so
.

As velocity moves with constant velocity of 3.5 m/s, therefore we can use formula

From above substituting t,
.
Now substituting all the given values and g = 9.8 m/s^2, we get
.
Thus, the distance the boat was from the point of impact when the key was released is 10.60 m.
The equilibrant force of the two given forces is 14.14 N.
<h3 /><h3 /><h3>What is equilibrant force?</h3>
- This is a single force that balances other given forces.
The given parameters:
- First force, F₁ = 10 N
- Second force, F₂ = 10 N
- Angle between the forces, θ = 90⁰
The equilibrant force of the two given forces is calculated as follows;

Thus, the equilibrant force of the two given forces is 14.14 N.
Learn more about equilibrant force here: brainly.com/question/8045102
The answer is C. the earths mantle because the wood in this case is the surface