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1 year ago

A fast-moving car has 0.5 MJ of kinetic energy.

Physics

1 answer:

DerKrebs [107]1 year ago

6 0

Answer:

-0.5 MW

Explanation:

For this we can use the principle of work and energy, which states that:

T₁ + ∑U₁₋₂ = T₂

Where T is kinetic energy (in situations one and two) and U is the sum of all work done (between situations one and two).

So, since the car is first moving with a kinetic energy of 0.5 MJ:

T₁ = 0.5 MJ = 0.5 · 10⁶ J

On top of this, we know that the car comes to a halt, using this as situation 2:

T₂ = 0 J

Filling in the equation:

⇒ 0.5 · 10⁶ + U = 0

⇒ U = -0.5· 10⁶ [W] (unit of work is watts)

= -0.5 MW

Thinking about the sign convention, we see that the brake force will point to the back of the car (backward), and the distance the car will travel before stopping will be forward, oposite directions and thus negative work.

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A small lab cart and one of larger mass collide and rebound off each other. Which of them has the greater average force on it du

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This normal force is always equal and opposite on two balls which means this force will follow Newton's III law

It will be same in magnitude but opposite in the direction

So here correct answer would be

<u><em>They both experience the same magnitude of the collision force.</em></u>

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2 years ago

A horizontal uniform meter stick supported at the 50-cm mark has a mass of 0.50 kg hanging from it at the 20-cm mark and a 0.30

ElenaW [278]

Answer:

70 cm

Explanation:

0.5 kg at 20 cm

0.3 kg at 60 cm

x = Distance of the third 0.6 kg mass

Meter stick hanging at 50 cm

Torque about the support point is given by (torque is conserved)

$0.5(50-20)=0.3(60-50)+0.6x\\\Rightarrow x=\dfrac{0.5(50-20)-0.3(60-50)}{0.6}\\\Rightarrow x=20\ cm$

The position of the third mass of 0.6 kg is at 20+50 = 70 cm

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2 years ago

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which pole of a compass needle points north ? please give simple answer with little explaining if any :)

Mumz [18]

I think the North Pole
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2 years ago

Consider a vortex filament of strength Γ in the shape of a closed circular loop of radius R. Consider also a straight line throu

Sedbober [7]

Answer:

$\vec{V} = \frac{\Gamma}{2R}\vec{A}$

Explanation:

We define our values according to the text,

R= Radius

$\vec{V} =$ Velocity

$\Gamma =$ Strenght of the vortex filament

From this and in a vectorial way we express an elemental lenght of this filmaent as $\vec{dl}$ . So,

$\vec{dl}x\vec{r} = R*dl*\vec{A}$

Where $\vec{A}$ imply a vector acting perpendicular to both vectors.

Applying Biot-Savart law, we have,

$\vec{V} =\frac{\Gamma}{4\pi}\int\frac{\vec{dl}x\vec{r}}{r^3}$

Substituting the preoviusly equation obtained,

$\vec{V} = \frac{\Gamma}{4\pi}\int\frac{R*dl*\vec{A}}{R^3}$

$\vec{V} = \frac{\Gamma}{4\pi R^2}\int^{2\pi R}_0 dl*\vec{A}$

$\vec{V} = \frac{\Gamma(2\pi R \vec{A})}{4\pi R^2}$

So we can express the velocity induced is,

$\vec{V} = \frac{\Gamma}{2R}\vec{A}$

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2 years ago

Ladybug walks 10 cm forward and 5 cm backwards in 20 seconds what is the average speed of ladybug what is the average velocity

lbvjy [14]

Answer:

Average speed = 0.0075 m/s

Average velocity = 0.0025 m/s along forward direction

Explanation:

Speed is the ratio of distance and time and velocity is the ratio of displacement and time.

Distance traveled = 10 + 5 = 15 cm = 0.15 m

Displacement = 10 - 5 = 5 cm = 0.05 m

Time = 20 seconds

$\texttt{Average speed = }\frac{\texttt{Distance}}{\texttt{Time}}\\\\\texttt{Average speed = }\frac{0.15}{20}=7.5\times 10^{-3}m/s\\\\\texttt{Average velocity = }\frac{\texttt{Displacement}}{\texttt{Time}}\\\\\texttt{Average velocity = }\frac{0.05}{20}=2.5\times 10^{-3}m/s$

Average speed = 0.0075 m/s

Average velocity = 0.0025 m/s along forward direction

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2 years ago

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