I think the corect answer would be C. When a police officer receives information that you are speeding in your vehicle, she is using the frequency of the wave to measure the Doppler Effect. As the speed of a vehicle increases, the greater the change of the frequency of the waves would be transmitted to the radar guns which is being used by the police officer. Doppler effect is an effect that is observed in sound and light waves as these waves move away or to the direction of the observer. This is being used in many applications like in astronomy, weather balloons, the radar guns,and for underwater researches.
Speed<span> has the dimensions of distance divided by time. The </span>SI unit<span> of </span>speed<span> is the metre per second, but the most common </span>unit<span> of </span>speed<span> in everyday usage is the kilometre per hour or, in the US and the UK, miles per hour.</span>
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Answer:</h2>
The force is <u>B. gravitational force</u>.
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Explanation:</h2>
A force from a fixed center point which directs the moving body towards it is called centripetal force. This force makes the body to follow a curved path.
In the case of sun and earth, the force which makes the earth follow a particular orbit and hold it in the same orbit is the gravitational force exhibited by the sun.
Gravitational force is a pulling force that attracts objects with mass. Every object in the universe is pulling on another object even when they are very far from each other.
Options
a. The worker carried the lunch up to the 53rd floor in the elevator.
b. The worker got a ride in a helicopter to the top of the 68-floor building and then carried the lunch down in the elevator to the 53rd floor?
c. The Worker carried it up the stairs to the 53rd floor.
d. Gravitational potential energy does not depend on the path taken.
Answer:
The gravitational Energy would remain the same in all cases.
Explanation:
Gravitational Energy is a conservative energy and its potential energy comes from gravitational actions.
An instance is when someone lifts a weight from the floor to a certain height and then dropped the weight back to the floor; the work done by the field will not be altered at all; it'll be the same throughout.
If otherwise, it'll be against thermodynamics 2nd law of physics because the object would have remaining energy after returning to the starting point,
For this reason, the gravitational potential energy only depends from the height, and is independent from the path taken to reach there.
Answer:
μ = 0.36
Explanation:
This exercise must be solved in parts
Let's start by finding the acceleration of the train, using the kinematics relations
v = v₀ - a t
a = 
let's reduce the magnitudes to the SI system
v = 66 mi / h (5280 ft / 1mile) (1h / 3600s) = 96.8 ft / s
v₀ = 144 mi / h = 211.2 ft / s
let's calculate
a = 
a = - 9.53 ft / s²
Now we can use Newton's second law, for this let's set a reference system with the x axis parallel to the slope of the hill
let's break down the weight
sin 5 = Wₓ / W
cos 5 = W_y / W
Wₓ = W sin 5
W_y = W cos 5
Y axis
N- W_y = 0
N = W cos 5
X axis
Wₓ -fr = m a
mg sin 5 - fr = ma
the friction force has the expression
fr = μ N
fr = μ W cos 5
we substitute
mg sin 5 - μ mg cos 5 = ma
g sin 5 - μ g cos 5 = a
μ = 
μ = 
let's calculate
μ = tan 5 - (-9.53) / 32 cos 5
μ = 0.08749 + 0.2733
μ = 0.36
