Answer:

Explanation:
This is a projectile motion problem. We will first separate the motion into x- and y-components, apply the equations of kinematics separately, then we will combine them to find the initial velocity.
The initial velocity is in the x-direction, and there is no acceleration in the x-direction.
On the other hand, there no initial velocity in the y-component, so the arrow is basically in free-fall.
Applying the equations of kinematics in the x-direction gives

For the y-direction gives

Combining both equation yields the y_component of the final velocity

Since we know the angle between the x- and y-components of the final velocity, which is 180° - 2.8° = 177.2°, we can calculate the initial velocity.

The Doppler effect says that the observed wavelength is shortened
when the source is approaching the observer, and lengthened when
the source is receding from the observer.
All we can say about the police car and its siren is that the sound/color
has a shorter wavelength as it approaches us, and a longer wavelength
as it recedes.
Any of these pairs of answers would say that:
A -- A
C -- A
D -- A
or
D -- D
For each of these pairs, the second wavelength is longer than the first one.
(We don't know which pair is the actual one, because we don't know the actual color of the police car.)
Explanation:
Formula for the electric field due to the infinite sheet of charge is as follows.
E =
where,
= surface charge density
Now, formula for electric force acting on the proton is as follows.
F = eE
where, e = charge of the proton
According to the Newton's second law of motion, the net force acting on the proton is as follows.
F = ma
a = 
= 
= 
According to the kinematic equation, speed of the proton in perpendicular direction is as follows.

= 
= 
= 683.974 m/s
Hence, total speed of the proton is as follows.
v' =
= 
= 
= 1178.73 m/s
Therefore, we can conclude that speed of the proton is 1178.73 m/s.
Explanation:
Given that,
Mass of the block, m = 12.2 kg
Initial velocity of the block, u = 6.65 m/s
The coefficient of kinetic friction, 
(a)The force of kinetic friction is given by :

mg is the normal force
So,

(b) Net force acting on the block in the horizontal direction,
f = ma
a is the acceleration of the block

(c) Let d is the distance covered by the block before coming to the rest. Using third equation of motion as follows :

Hence, this is the required solution.