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3 years ago

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A train is traveling at a speed of 75km/hr. The brakes are applied to produce a uniform acceleration of -0.5 m/s2.Find how far t

he train goes before it stops?

1 answer:

NNADVOKAT [17]3 years ago

7 0

Answer:

your answer would be 21m

Explanation:

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A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii. If the three of them are released simultaneou

Roman55 [17]

Answer:

The solid sphere will reach the bottom first.

Explanation:

In order to develop this problem and give it a correct solution, it is necessary to collect the concepts related to energy conservation. To apply this concept, we first highlight the importance of conserving energy so we will match the final and initial energies. Once this value has been obtained, we will concentrate on finding the speed, and solving what is related to the Inertia.

In this way we know that,

$\Delta KE = - \Delta PE$

$KE_t + KE_r = mgh$

We know as well that the lineal and angular energy are given by,

$KE_r = \frac{1}{2}I\omega^2$

And the tangential kinetic energy as

$KE_t = \frac{1}{2} mv^2$

Where $\omega = \frac{v}{R}$

Replacing

$\frac{1}{2}mv^2 + \frac{1}{2}I\frac{v}{R} = mgh$

Re-arrange for v,

$v=\sqrt{\frac{2mgh}{m+I/R^2}}$

We have here three different objects: solid cylinder, hollow pipe and solid sphere. We need the moment inertia of this objects and replace in the previous equation found, then,

For hollow pipe:

$I_{hp}=mR^2$

$v_{hp}=\sqrt{\frac{2mgh}{m+(mR^2)/R^2}}$

$v_{hp}=\sqrt{\frac{2mgh}{m+m)}$

$v_{hp}=\sqrt{gh}$

For solid cylinder:

$I_{sc}=\frac{1}{2}mR^2$

$v_{sc}=\sqrt{\frac{2mgh}{m+(1/2mR^2)/R^2}}$

$v_{sc}=\sqrt{\frac{2mgh}{m+1/2m}}$

$v_{sc}=\sqrt{\frac{3}{4}gh}$

For solid sphere,

$I_{ss}=\frac{2}{5}mR^2$

$v_{ss}=\sqrt{\frac{2mgh}{m+(2/5mR^2)/R^2}}$

$v_{ss}=\sqrt{\frac{2mgh}{m+2/5m}}$

$v_{ss}=\sqrt{\frac{10}{7}gh}$

Then comparing the speed of the three objects we have:

$v_{hp}$

$\sqrt{gh}$

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4 years ago

What is the decibel level of the noise in a typical classroom?

maks197457 [2]

I think it is 100 dB .I holp it is help.

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3 years ago

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Which type of glacier is found in mountainous areas

Sergio039 [100]

I believe that they are Ice Glaciers.

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3 years ago

How far would a spacecraft moving in a circular orbit 500 km above Pluto's surface travel during that time?

Ilia_Sergeevich [38]

Answer:

The speed of the spacecraft should be 719.35m/s

Explanation:

if the spacecraft is orbiting the planet with a circular orbit, the gravitational force must act as a centripetal force. This means:

$F_G=F_c\\\frac{GmM}{d^2}=m\frac{v^2}{d}$

In this case, the pluto's mass M is 1.3099·10^22 kg. The radius of the planet R is 1188.3Km and G is the gravitational constant. Therefore:

$\displaystyle\frac{G M}{d^2}=\frac{v^2}{d}\\v=\sqrt{\frac{GM}{d} } =\sqrt{\frac{GM}{(R + 500km)} } =719.35m/s$

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Convection occurs when thermal energy is transferred by the movement of

madam [21]

Answer:

Convection is the transfer of thermal energy from one place to another by the movement of gas or liquid particles. How does this happen? As a gas or liquid is heated, the substance expands. This is because the particles in liquids and gases gain kinetic energy when they are heated and start to move faster.

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