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anzhelika [568]
3 years ago
12

A roller coaster starts from rest at its highest point and then descends on its (frictionless) track. its speed is 40 m/s when i

t reaches ground level. part a what was its speed when its height was half that of its starting point? what was its speed when its height was half that of its starting point? 33 m/s 14 m/s 20 m/s 28 m/s
Physics
1 answer:
Alenkinab [10]3 years ago
5 0

Given that,

Initial velocity , Vi = 0

Final velocity , Vf = 40 m/s

Acceleration due to gravity , a = 9.81 m/s²

Distance can be calculated as,

2as = Vf² - Vi²

2 * 9.81 *s = 40² - 0²

s = 81.55 m

For half height, that is, s = 40.77m

Vf= ??

2as = Vf² - Vi²

2 * 9.81 * 40.77 = Vf² - 0²

Vf² = 800

Vf = 28.28 m/s

Therefore, speed of roller coaster when height is half of its starting point will be 28 m/s.  

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Answer:

t = 37.6 s

Explanation:

As we know that train is initially moving with the speed

v_i = 75.1 km/h

now we know that

v_i = 20.86 m/s

now the final speed of the train when it crossed the crossing

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v_f = 4.17 m/s

now we can use kinematics here

v_f^2 - v_i^2 = 2 a d

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Now the time to cross that junction is given as

v_f - v_i = at

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2 years ago
Why are you able to observe the Doppler effect on earth with sound waves but not with light waves?
VladimirAG [237]

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7 0
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Water drips from a shower head (the sprayer at the top of the shower) and falls onto the floor 2.3 m below. The droplets are fal
Maurinko [17]

Answer:

0.767m

Explanation:

We are given that the time interval between each droplet is equal.

We are also given that the fourth drop is just dripping from the shower when the first hits the floor.

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The distance between each drop has to be the same given that they fall at equal time intervals.

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We can then partition the entire height of the system into three parts (as shown in the diagram).

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Therefore, at the time the first drop hits the floor, the third drop is only 0.767 m below the shower head.

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56C



Hope that helps, Good luck! (:
5 0
3 years ago
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