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DIA [1.3K]
3 years ago
11

A train is moving in the positive direction down a track. First the train speeds up, and then it slows down. What is its acceler

ation?
A. The train has positive acceleration throughout.
B.The train has negative acceleration throughout.
C.The train first has positive acceleration and then negative acceleration.
D.The train first has negative acceleration and then positive acceleration.
Physics
2 answers:
tatuchka [14]3 years ago
8 0
C.

The train first sped up, giving it a positive acceleration in the beginning. This eliminates D since that choice states that it begins with a negative acceleration. This also eliminates B since that choice states that the train only had a negation acceleration.

Next, the train slows down, giving it a negative acceleration. We’re looking for the answer choice that starts with a positive acceleration and ends with a negative one. This makes C the correct answer. Hope this helps!
Marina86 [1]3 years ago
8 0

Answer:

The answer is <u><em>The train first has positive acceleration and then negative acceleration. </em></u>

<u><em></em></u>

Explanation: I answered the question right on my online school quiz.

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A politician running for office tells a crowd at a rally that the only way to keep the food chain safe is to stop allowing the g
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B. No. He presented no scientific data to support his claim.

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3 years ago
If the accepted value of a wave is 121 m/s, who has the most accurate method of measuring the speed of a wave?
qaws [65]
The answer would be erin out of all of them thank me later :)
5 0
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2. For a rotating rigid body, which of the following statements is NOT correct?
AfilCa [17]

Answer:

                                                dasgfwe

Explanation:

6 0
3 years ago
When might it be harder to stop a vehicle moving at 30 km/h than one moving at 60 km/h?
rodikova [14]

Answer:

when the momentum of the vehicle moving at 30 km/h is higher than the one from the vehicle moving at 60 km/h

Explanation:

It's much harder to stop a freight truck moving at 30 km/h than a hot wheels car moving at 60 km/h.

4 0
2 years ago
To visit your favorite ice cream shop, you must travel 490 m west on Main Street and then 920 m south on Division Street. Suppos
topjm [15]

Answer:

a) The magnitude of your average velocity during the 121 s is 8.61 m/s.

b) The direction of the average velocity is 61.9° south of west.

c) Your average speed during the trip is 11.7 m/s

Explanation:

Hi there!

a) The average velocity (a.v) is calculated as the displacement divided by the time it took to do such a displacement.

The displacement is calculated as the distance between the initial position and the final position:

Displacement = Δ(x,y) = final position - initial position

Let's consider that your initial position is the origin of our frame of reference and let's also consider that west and south are positive directions (+x and +y respectively). Then the displacement vector will be:

Δ(x,y) = final positon - initial position

Δ(x,y) = (490, 920) m - (0, 0) m = (490, 920) m

The average velocity will be:

a.v = Δ(x,y) / t

a.v = (490, 920) m / 121 s

a.v = (4.05, 7.60) m/s

The magnitude of the average velocity is calculated as follows:

 

The magnitude of your average velocity during the 121 s is 8.61 m/s.

b) To find the direction of the average velocity, we have to use trigonometric rules of right triangles. Notice that the x and y-components of the average velocity (vx and vy) together with the average velocity vector (v), with magnitude 8.61 m/s, form a triangle (see figure).

Also, notice that v is the hypotenuse of the triangle and that vx is the side adjacent to the angle θ while vy is the side opposite to θ.

Using trigonometry, we can calculate the value of the angle θ:

cos θ = adjacent side / hypotenuse

cos θ = vx / v

cos θ = 4.05 m/s / 8.61 m/s

θ = 61.9°

The direction of the average velocity is 61.9° south of west.

c) The average speed (a.s) is calculated as the traveled distance (d) divided by the time it took to cover that distance (t). In total, you traveled (490 m + 920 m) 1410 m in 121 s, then the average speed will be:

a.s = d/t

a.s = 1410 m / 121 s

a.s = 11.7 m/s

Your average speed during the trip is 11.7 m/s

5 0
3 years ago
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