D. mechanical energy is transformed into sound energy.
Our planet is closed system because there is a limit of how much matter could be exchanged.
Answer:
Explanation:
<u>Sum of Vectors in the Plane</u>
Given two vectors
They can be expressed in their rectangular components as
The sum of both vectors can be done by adding individually its components
If the vectors are given as a magnitude and an angle 
, each component can be found as
The first vector has a magnitude of 3.14 m and an angle of 30°, so
The second vector has a magnitude of 2.71 m and an angle of -60°, so
The sum of the vectors is
Finally, we compute the magnitude of the sum
Answer:
The power exerted by the student is 51.2 W
Explanation:
Given;
extension of the elastic band, x = 0.8 m
time taken to stretch this distance, t = 0.5 seconds
the spring constant, k = 40 N/m
Apply Hook's law;
F = kx
where;
F is the force applied to the elastic band
k is the spring constant
x is the extension of the elastic band
F = 40 x 0.8
F = 32 N
The power exerted by the student is calculated as;
P = Fv
where;
F is the applied force
v is velocity = d/t
P = F x (d/t)
P = 32 x (0.8 /0.5)
P = 32 x 1.6
P = 51.2 W
Therefore, the power exerted by the student is 51.2 W
The average acceleration of the car in this process is -2 m/s²
<h3>
What is Acceleration ?</h3>
Acceleration can be defined as change in velocity per time taken. It is a vector quantity. That is, it has both the magnitude and direction. It is measured in m/s²
Given that a velocity of a car decreases from 28m/s to 20m/s in a time of 4 seconds. Then,
- Initial velocity u = 28 m/s
- Final velocity v = 20 m/s
From the definition of acceleration,
a = Δv / t
a = ( 20 - 28 ) / 4
a = -8 / 4
a = - 2 m/s²
Therefore, the average acceleration of the car in this process is -2 m/s² which mean that the car is decelerating.
Learn more about Deceleration here: brainly.com/question/25311290
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