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IgorLugansk [536]
3 years ago
5

A crate is given a push across a horizontal surface. The crate has a mass m, the push gives it an initial speed of 1.90 m/s, and

the coefficient of kinetic friction between the crate and the surface is 0.120.
(a) Use energy considerations to find the distance (in m) the crate moves before it stops.

(b) Determine the stopping distance (in m) for the crate if its initial speed is doubled to 3.80 m/s.
Physics
1 answer:
Roman55 [17]3 years ago
3 0

Answer:

a) s = 1.534\,m, b) s = 6.135\,m

Explanation:

a) The energy equation for the crate is modelled after the Principle of Energy Conservation and Work-Energy Theorem. Changes in gravitational potential energy can be neglected due to the information of a horizontal surface:

K_{A} = W_{loss}

\frac{1}{2}\cdot m \cdot v^{2} = \mu_{k} \cdot m \cdot g\cdot s

The distance that crate needs to cover before stopping is:

s = \frac{v^{2}}{2\cdot \mu_{k}\cdot g}

s = \frac{(1.90\,\frac{m}{s} )^{2}}{2\cdot (0.120)\cdot (9.807\,\frac{m}{s^{2}} )}

s = 1.534\,m

b) The stopping distance is:

s = \frac{(3.80\,\frac{m}{s} )^{2}}{2\cdot (0.120)\cdot (9.807\,\frac{m}{s^{2}} )}

s = 6.135\,m

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2 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

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What is the intensity in W/m2 of a laser beam used to burn away cancerous tissue that, when 85.0% absorbed, puts 470 J of energy
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Answer:

26036485.6433 W/m²

Explanation:

E= Energy = 470 J

t = Time = 4 seconds

d = Diameter = 2.6 mm

Power is given by

P=\dfrac{E}{t}

Intensity is given by

I=\dfrac{P}{\pi r^2}\\\Rightarrow 0.85I=\dfrac{E}{t\dfrac{\pi}{4} d^2}\\\Rightarrow I=\dfrac{470}{0.85\times 4\times \dfrac{\pi}{4}\times (2.6\times 10^{-3})^2}\\\Rightarrow I=26036485.6433\ W/m^2

The intensity of the laser beam is 26036485.6433 W/m²

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A point charge of 5.0 x 10^-7 C moves to the right at 2.6 x 10^5 m/s in a magnetic field that is directed into the screen and ha
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The magnitude of the magnetic force acting on the charge is 2.34×10⁻³ N.

<h3>What is magnetic force?</h3>

A magnetic force is the force that act in a magnetic field.

To calculate the magnetic force, we use the formula below.

Formula:

  • F = qvB.........Equation 1

Where:

  • F = magnetic force
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From the question,

Given:

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Substitute these values into equation 2

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Hence, the magnitude of the magnetic force acting on the charge is 2.34×10⁻³ N.

Learn more about magnetic force here: brainly.com/question/2279150

#SPJ12

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Why do teachers give such hard questions? anyways hopefully your question will get answered! (btw i also need the points but yeah gl!!!)

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