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elena-s [515]
2 years ago
12

A train sounds its whistle at a constant frequency as it passes by the platform. Compared to the sound emitted by the whistle, t

he sound that people on the platform hear as the train moves away has a frequency that is ...
-higher
-the same
-lower
-exactly half
Physics
1 answer:
Fittoniya [83]2 years ago
4 0

Answer: Higher.

Explanation: The doppler effect essentially. "The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding."

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In 2007, michael carter (u.s.) set a world record in the shot put with a throw of 24.77 m. what was the initial speed of the sho
Serga [27]

The initial speed of the shot is 15.02 m/s.

The Shot put is released at a height y<em> </em>from the ground with a speed u. It is released at an angle θ to the horizontal. In a time t, the shot put travels a distance <em>R</em> horizontally.

Pl refer to the attached diagram.

Resolve the velocity u into horizontal and vertical components, u ₓ=ucosθ and uy=u sinθ. The horizontal component remains constant in the absence of air resistance, while the vertical component varies due to the action of the gravitational force.

Write an expression for R.

R=u_xt=(ucos \theta)t

Therefore,

t=\frac{R}{ucos\theta} .......(1)

In the time t, the net displacement of the shotput is y in the downward direction.

Use the equation of motion,

y=u_yt-\frac{1}{2}gt^2=(usin\theta) t-\frac{1}{2}gt^2

Substitute the value of t from equation (1).

y=(ucos\theta)(\frac{R}{ucos\theta} )-\frac{1}{2} g(\frac{R}{ucos\theta} )^2\\ =Rtan\theta-(\frac{gR^2}{2u^2cos^2\theta} )

Substitute -2.10 m for y, 24.77 m for R and 38.0° for θ and solve for u.

y=Rtan\theta-(\frac{gR^2}{2u^2cos^2\theta} )\\ (-2.10m)=(24.77 m)(tan38.0^o)-\frac{(9.8 m/s^2)(24.77m)^2}{2u^2(cos38.0^o)^2} \\ u^2=225.71(m/s)^2\\ u=15.02m/s

The shot put was thrown with a speed 15.02 m/s.




7 0
3 years ago
How do you find speed of a ball at maximum height
Crazy boy [7]

Explanation:

At maximum height, the vertical component of a ball's speed is 0.  So the net speed is equal to whatever the horizontal component of the ball is.  If the ball is launched straight up, the speed at the highest point is simply 0.

5 0
3 years ago
Use tug of war to explain balanced and unbalanced forces
Dimas [21]
Forces equal the flag doesn't move either direction

Unequal forces the flag moves in the direction of the greater magnitude force
4 0
4 years ago
All of the noble gases, Group 18, have eight valence electrons in its outer shell (excluding helium which only has two). Which o
ikadub [295]

Answer:

Zero or +2

Explanation:

The noble gases already have a avplete outermost shell. They are the least reactive elements of earth?

Their normal oxidation number is zero but some have been shown to be reactive.

6 0
3 years ago
Read 2 more answers
On Earth, a brick has a mass of 10 kg and a weight of 5 lbs. What predictions could we make about the mass and weight of the bri
belka [17]

Answer:

Mass remains constant but weight reduces

Explanation:

Mass is the amount of matter in an object so whether on moon or any other planet, it does not change despite the changes in acceleration.

Weight is a product of mass and acceleration due to gravity, expressed as W=mg where m is the mass, W is weight and g is acceleration. From the above formula, it is evident that when you decrease g, then W also decreases while m is constant. Similarly, when m is constant and g is increased then W also increases.

Therefore, for this case, since g decreases, the weight decreases but mass remains constant.

8 0
3 years ago
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