Jenny is doing her homework when Jenny writes, the pencil exerts a force of 5N on the paper. The area of the pencil in contact w
2 answers:
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Answer:
-6112.26 J
Explanation:
The initial kinetic energy, is given by
} where m is the mass of a body and
is the initial velocity
The final kinetic energy, is given by
where
is the final velocity
Change in kinetic energy, is given by
Since the skater finally comes to rest, the final velocity is zero. Substituting 0 for and 12.6 m/s for
and 77 Kg for m we obtain
From work energy theorem, work done by a force is equal to the change in kinetic energy hence for this case work done equals <u>-6112.26 J</u>
Answer:
Choices A, B, and C are correct.
Explanation:
Let us look at each of the choices one by one:
A. It is a vector
Yes. Velocity is a vector, or it's a speed with direction.
B. It is the change in displacement divided by the change in time.
Yes. The velocity can be written as
where is the displacement—a vector quantity.
C. It can be measured in meters per second.
Yes. The units of velocity are m/s, but also with a unit vector indicating the direction.
D. It is the slope of the acceleration vs. time graph.
Nope. The velocity is the slope of displacement vs. time graph.
Hence, only choices A, B, and C are correct.
Complete Question
A commuter train passes a passenger platform at a constant speed of 39.6 m/s. The train horn is sounded at its characteristic frequency of 350 Hz.
(a)
What overall change in frequency is detected by a person on the platform as the train moves from approaching to receding
(b) What wavelength is detected by a person on the platform as the train approaches?
Answer:
a
b
Explanation:
From the question we are told that
The speed of the train is
The frequency of the train horn is
Generally the speed of sound has a constant values of
Now according to dopplers equation when the train(source) approaches a person on the platform(observe) then the frequency on the sound observed by the observer can be mathematically represented as
substituting values
Now according to dopplers equation when the train(source) moves away from the person on the platform(observe) then the frequency on the sound observed by the observer can be mathematically represented as
substituting values
The overall change in frequency is detected by a person on the platform as the train moves from approaching to receding is mathematically evaluated as
Generally the wavelength detected by the person as the train approaches is mathematically represented as