V: there would be no seasons and humanity would suffer
Answer:
a) E = 2.00 10³ J
, b) I = 6.66 10⁻⁶ N s
, c) F = 1.66 10⁻⁶ N
Explanation:
a) The intensity is defined as the power per unit area
I = P / A
P = I A
Power is energy for time
P = E / t
We replace
E / t = I A
E = I A t
E = 1.0 10³ 2.0 1.00
E = 2.00 10³ J
b) The moment is
p = U / c
In the case of a reflection the speed is reversed, so the moment
Δp = 2 U / c
I = Δp
I = 2 U / c
I = 2.00 10³/3 10⁸
I = 6.66 10⁻⁶ N s
c) The defined impulse is
I = F t
F = I / t
For a time of 1 s
F = 6.66 10⁻⁶ / 1
F = 1.66 10⁻⁶ N
d) Suppose n small mass mirror m = 10 10⁻³ kg, we write Newton's second law
F = ma
a = F / m
a = 1.66 10⁻⁶ / 10 10⁻³
a = 1.66 10⁻⁴ m / s
We see that the acceleration is very small and attended to increase the mass of the mirror will be less and less, so the assumption of no twisting of the mirror is very reasonable
Walking at a speed of 2.1 m/s, in the first 2 s John would have walked
(2.1 m/s) (2 s) = 4.2 m
Take this point in time to be the starting point. Then John's distance from the starting line at time <em>t</em> after the first 2 s is
<em>J(t)</em> = 4.2 m + (2.1 m/s) <em>t</em>
while Ryan's position is
<em>R(t)</em> = 100 m - (1.8 m/s) <em>t</em>
where Ryan's velocity is negative because he is moving in the opposite direction.
(b) Solve for the time when they meet. This happens when <em>J(t)</em> = <em>R(t)</em> :
4.2 m + (2.1 m/s) <em>t</em> = 100 m - (1.8 m/s) <em>t</em>
(2.1 m/s) <em>t</em> + (1.8 m/s) <em>t</em> = 100 m - 4.2 m
(3.9 m/s) <em>t</em> = 95.8 m
<em>t</em> = (95.8 m) / (3.9 m/s) ≈ 24.6 s
(a) Evaluate either <em>J(t)</em> or <em>R(t)</em> at the time from part (b).
<em>J</em> (24.6 s) = 4.2 m + (2.1 m/s) (24.6 s) ≈ 55.8 m
B: 210.8 rounded to 210 is totally wrong, and the reason why is because 210.8 rounded to the nearest whole number is 211, not 210. So B is the one with the error (this option is correct) and the other user that said D, is wrong since 18.42 does round to 18.4.
Hope this helped!
Nate
Answer:
(a): The magnitude of the electric force on the small sphere = 
(b): Shown below.
Explanation:
<u>Given:</u>
- m = mass of the small sphere.
- q = charge on the small sphere.
- L = length of the silk fiber.
= surface charge density of the large vertical insulating sheet.
<h2>
(a):</h2>
When the dimensions of the sheet is much larger than the distance between the charge and the sheet, then, according to Gauss' law of electrostatics, the electric field experienced by the particle due to the sheet is given as:
<em>where,</em>
is the electrical permittivity of the free space.
The electric field at a point is defined as the amount of electric force experienced by a unit positive test charge, placed at that point. The magnitude electric field at a point and the magnitude of the electric force on a charge q placed at that point are related as:
Thus, the magnitude of the electric force on the small sphere is given by
The sheet and the small sphere both are positively charged, therefore, the electric force between these two is repulsive, which means, the direction of the electric force on the sphere is away from the sheet along the line which is perepndicular to the sheet and joining the sphere.
<h2>
(b):</h2>
When the sphere is in equilibrium, the tension in the fiber is given by the resultant of the weight of the sphere and the electric force experienced by it as shown in the figure attached below.
According to the fig.,
<em>where,</em>
= electric force on the sphere, acting along left.
= weight of the sphere, acting vertically downwards.
<em />
g is the acceleration due to gravity.
