A because when gravity and the force are equilibrium it tend to be equal or stay at rest or constant velocity. But when the force of a plane is less than the force of gravity it will go down to the ground. Unless when the force of a plane is greater than the force of gravity, the plane will move upward at increasing rate. 
Hope this helps
        
             
        
        
        
Answer:
B = 6.18 10⁻⁶ T  
 the magnetic field is in the negative direction of the y axis
Explanation:
The magnetic force is given by
          F = q v x B
as in the exercise indicate that the velocities perpendicular to the magnetic field,
          F = q v B
Newton's second law is
          F = m a
 let's substitute
          q v B = m a
          B = m a / q v
let's calculate
          B = 9.1 10⁻³¹ 2.50 10¹³ / (1.6 10⁻¹⁹ 2.30 10⁷)
          B = 6.18 10⁻⁶ T
The direction of the field can be obtained with the right hand rule, where the thumb points in the direction of the velocity, the fingers extended in the direction of the magnetic field and the palm in the direction of the force for a positive charge.
In the exercise indicate that the velocity is the z axis
the acceleration and therefore the force in the x axis
therefore the magnetic field is in the negative direction of the y axis
 
        
             
        
        
        
This is the Doppler effect.
1. As the sound leaves the horn the sound waves are at first close to each other and as they move outwards they become further apart. The closer the sound waves are the louder the noise.
As the car gets the closer the sound waves get closer, so the horn becomes louder.
2. As the horn moves away, the sound waves become less frequent, causing the pitch to get lower.
 
        
             
        
        
        
Answer:
v₀ₓ = 63.5 m/s
v₀y = 54.2 m/s
Explanation:
First we find the net launch velocity of projectile. For that purpose, we use the formula of kinetic energy:
K.E = (0.5)(mv₀²)
where,
K.E = initial kinetic energy of projectile = 1430 J
m = mass of projectile = 0.41 kg
v₀ = launch velocity of projectile = ?
Therefore,
1430 J = (0.5)(0.41)v₀²
v₀ = √(6975.6 m²/s²)
v₀ = 83.5 m/s
Now, we find the launching angle, by using formula for maximum height of projectile:
h = v₀² Sin²θ/2g
where,
h = height of projectile = 150 m
g = 9.8 m/s²
θ = launch angle
Therefore,
150 m = (83.5 m/s)²Sin²θ/(2)(9.8 m/s²)
Sin θ = √(0.4216)
θ = Sin⁻¹ (0.6493)
θ = 40.5°
Now, we find the components of launch velocity:
x- component = v₀ₓ = v₀Cosθ  = (83.5 m/s) Cos(40.5°)
<u>v₀ₓ = 63.5 m/s</u>
y- component = v₀y = v₀Sinθ  = (83.5 m/s) Sin(40.5°)
<u>v₀y = 54.2 m/s</u>
 
        
             
        
        
        
Color is what scientist use to determine the temperature of a star!
hope this helps!