1. An object in free fall will have an initial velocity equal to zero when: a. It is thrown vertically down

Physics

1 answer:

Ne4ueva [31]3 years ago

6 0

Answer:

b. It is dropped

Explanation:

If the initial velocity is zero, the object move from rest. That happens if the object is dropped

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An engine flywheel initially rotates counterclockwise at 6.55 rotations/s. Then, during 20.9 s, its rotation rate changes to 2.1

11Alexandr11 [23.1K]

Answer:

The average angular acceleration is -2.628 rad/s²

Explanation:

Counterclockwise = positive

Clockwise = -negative

Given;

initial rotation of the flywheel, θ₁ = 6.55 rotation/s

final rotation of the flywheel, θ₂ = - 2.19 rotation/s

The average angular acceleration is given by;

$\alpha = \frac{\delta \theta}{\delta t}\\\\ \alpha =\frac{\theta _2 - \theta_ 1}{t}\\\\ \alpha =\frac{-2.19 -6.55}{20.9} \\\\ \alpha =\frac{-8.74}{20.9}\\\\ \alpha = -0.4182 \ rotation / s^2\\\\ \alpha = \frac{-0.4182 \ rotation}{s^2}*\frac{2\pi \ radian}{rotation}\\\\ \alpha = -2.628 \ rad/s^2$

Therefore, the average angular acceleration is -2.628 rad/s²

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3 years ago

The battery charger for an mp3 player contains a step-down transformer with a turns ratio of 1:38, so that the voltage of 120 v

matrenka [14]

Transformer contains two coils: primary and secondary. They allow change of voltage to lower or higher value. In first case we have step-down and in second case we have step-up transformer.
Formula used for transformer is: $\frac{N_{1} }{N_{2}} = \frac{V_{1}}{V_{2}}$

Where:N1 = number of turns on primary coilN2 = number of turns on secondary coilV1 = voltage on primary coilV2 = voltage on secondary coil
In a step-down transformer primary coil has more turns than secondary coil. So the ratio 1:38 means that for each turn on secondary coil we have 38 turns on primary coil.
We can solve the equation for V2: $V_{2} = \frac{ V_{1}* N_{2} }{ N_{1} } \\ V_{2} = \frac{ 120* x }{ 38x} } \\ V_{2} = 3.16V$

Secondary coil provides voltage of 3.16V.

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3 years ago

Find the current passing through a circuit consisting of a battery and one resistor. The resistance has a retance of 2ohms and t

Bingel [31]

The current passing through a circuit consisting of a battery of 12 V and resistor of 2 ohms is 6 Ampere .

Explanation: