Answer:
1800J
Explanation:
Given parameters:
Weight of the book = 20N
Total distance covered = 45m + 15m + 30m = 90m
Unknown:
Total work performed on the books = ?
Solution:
To solve this problem we must understand that work done is the force applied to move a body through a certain distance.
So;
Work done = Force x distance
Work done = 20 x 90 = 1800J
We have that the speed over the ground of a mosquito flying 2 m/s relative to the air against a 2 m/s headwind is
X=0m/s
From the question we are told that
mosquito flying 2 m/s
against a 2 m/s headwind
Generally
The speed over the ground is the Flight Speed minus resistance speed
Generally the equation for the speed over the ground is mathematically given as
X=Flight Speed-resistance speed
Therefore
X=2-2
X=0m/s
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Answer:
A. 1.4 m/s to the left
Explanation:
To solve this problem we must use the principle of conservation of momentum. Let's define the velocity signs according to the direction, if the velocity is to the right, a positive sign will be introduced into the equation, if the velocity is to the left, a negative sign will be introduced into the equation. Two moments will be analyzed in this equation. The moment before the collision and the moment after the collision. The moment before the collision is taken to the left of the equation and the moment after the collision to the right, so we have:
where:
M = momentum [kg*m/s]
M = m*v
where:
m = mass [kg]
v = velocity [m/s]
where:
m1 = mass of the basketball = 0.5 [kg]
v1 = velocity of the basketball before the collision = 5 [m/s]
m2 = mass of the tennis ball = 0.05 [kg]
v2 = velocity of the tennis ball before the collision = - 30 [m/s]
v3 = velocity of the basketball after the collision [m/s]
v4 = velocity of the tennis ball after the collision = 34 [m/s]
Now replacing and solving:
(0.5*5) - (0.05*30) = (0.5*v3) + (0.05*34)
1 - (0.05*34) = 0.5*v3
- 0.7 = 0.5*v
v = - 1.4 [m/s]
The negative sign means that the movement is towards left
Answer:
the thickness of the film for destructive interference is 1 cm
Explanation:
We can assume that the radar wave penetrates the layer and is reflected in the inner part of it, giving rise to an interference phenomenon of the two reflected rays, we must be careful that the ray has a phase change when
* the wave passes from the air to the film with a higher refractive index
* the wavelength inside the film changes by the refractive index
λ = λ₀ / n
so the ratio for destructive interference is
2 n t = m λ
t = m λ / 2n
indicate that the wavelength λ = 2 cm, suppose that the interference occurs for m = 1, therefore it is thickness
t = 1 2/2 n
t = 1 / n
where n is the index of refraction of the anti-reflective layer. As they tell us not to take into account the change in wavelength when penetrating the film n = 1
t = 1 cm
So the thickness of the film for destructive interference is 1 cm
