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schepotkina [342]

2 years ago

14

A puck moves 2.35 m/s in a -22° direction. A hockey stick pushes it for 0.215 s, changing its velocity to 6.42 m/s in a 50.0° di

rection. What was the direction of the acceleration?

1 answer:

Andreyy892 years ago

7 0

The puck starts with velocity vector

$\vec v_0=\left(2.35\dfrac{\rm m}{\rm s}\right)(\cos(-22^\circ)\,\vec\imath+\sin(-22^\circ)\,\vec\jmath)=(2.18\,\vec\imath-0.880\,\vec\jmath)\dfrac{\rm m}{\rm s}$

Its velocity at time $t$ is

$\vec v=\vec v_0+\vec at$

Over the 0.215 s interval, the velocity changes to

$\vec v=\left(6.42\dfrac{\rm m}{\rm s}\right)(\cos50.0^\circ\,\vec\imath+\sin50.0^\circ\,\vec\jmath)=(4.13\,\vec\imath+4.92\,\vec\jmath)\dfrac{\rm m}{\rm s}$

Then the acceleration must have been

$\vec v=\vec v_0+(0.215\,\mathrm s)\vec a\implies\vec a=\dfrac{\vec v-\vec v_0}{0.215\,\rm s}=(9.06\,\vec\imath+27.0\,\vec\jmath)\dfrac{\rm m}{\mathrm s^2}$

which has a direction of about $71.4^\circ$ .

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In a bedridden patient recovering from a badly fractured femur, disuse atrophy in the thigh muscles is caused by _________.

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2 years ago

A solid cylindrical bar conducts heat at a rate of 25 W from a hot to a cold reservoir under steady state conditions. If both th

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Answer:

Using the new cylinder the heat rate between the reservoirs would be 50 W

Explanation:

Conduction could be described by the Law of Fourierin the form: $Q=kA\frac{T_1-T_2}{L}$ where $Q$ is the rate of heat transferred by conduction, $k$ is the thermal conductivity of the material, $T_1$ and $T_2$ are the temperatures of each heat deposit, $A$ is the cross area to the flow of heat, and ${L}$ is the distance that the flow of heat has to go.
For the original cylinder the Fourier's law would be: $kA_1\frac{T_1-T_2}{L_1}=25W$ , and if $A_1=\frac{\pi D_{1}^{2}}{4}$ , then the expression would be: $k\frac{\pi D_1^{2}}{4} \frac{T_1-T_2}{L_1}=25W$ where $D_1$ is the diameter of the original cylinder, and ${L_1}$ is the length of the original cylinder.
For the new cylinder, in the same fashion that for the first, Fourier's Law would be: $Q_2=k\frac{\pi D_2^2}{4}\frac{T_1-T_2}{L_2}$ ,where $Q_2$ is the heat rate in the second case, $D_2$ and ${L_2$ are the new diameter and length.
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2 years ago

An ocean liner is cruising at 10 meters/second and is about to approach a stationary ferryboat. A parcel is released from the oc

Afina-wow [57]

The parcel will undergo projectile motion, which means that it will have motion in both the horizontal and vertical direction.

First, we determine how long the parcel will fall using:

s = ut + 1/2 at²

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5.5 = (0)(t) + 1/2 (9.81)(t)²
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Now, we may use this time to determine the horizontal distance covered by the parcel by using:
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The horizontal velocity of the parcel will be equal to the horizontal velocity of the cruise liner.

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2 years ago

Find an expression for the torsional constant k in terms of the moment of inertia I of the disk and the angular frequency ω of s

sasho [114]

Answer:

Explanation:

The general equation for the disk with moment of inertia I when given small angular displacement $\theta$ is given by

$I\frac{\mathrm{d^2} \theta }{\mathrm{d} t^2}=-k\theta$

$\frac{\mathrm{d^2} \theta }{\mathrm{d} t^2}+\frac{k\theta }{I}=0$

Replacing

$\frac{k\theta }{I}=\omega ^2$

where $\omega$ is the angular frequency of oscillation

General solution for this Equation is given by

$\theta =\theta _{max}\sin \left ( \omega t+\phi \right )$

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2 years ago

4. A cylindrical tube has a length of 14.4cm and a radius of 1.5cm and is filled with a colorless gas. If the density of the gas

professor190 [17]

Answer:

Mass, m of gas is 0.2504 grams.

Explanation:

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π represents pie

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h represents height or length.

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$V = 2 * 3.142 * 2.25 * 14.4$

$V = 203. 6016$

Therefore, the volume of the cylindrical tube is 203. 6016cm³

Density can be defined as mass all over the volume of an object.

Simply stated, density is mass per unit volume of an object.

Mathematically, density is given by the formula;

$Density = \frac{mass}{volume}$

$Mass = density * volume$

Substituting into the equation, we have;

$Mass = 0.00123 * 203. 6016$

Mass = 0.2504g.

5 0

2 years ago