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2 years ago

11

A skateboarder rolls horizontally off the top of a staircase and lands at the bottom. The staircase has a horizontal length of 1

2.0 with a vertical drop of 2.00. We can ignore air resistance.

1 answer:

TiliK225 [7]2 years ago

3 0

Answer: 18.8 m/s

Explanation:

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When the starter motor on a car is engaged, there is a 290 A current in the wires between the battery and the motor. Suppose the

Tema [17]

Answer:

$33.6\times10^{-4}}\text{ m}$ = 3.36 mm

Explanation:

From Ohm's law,

$V = IR$ (Voltage = Current * Resistance)

$R = \dfrac{V}{I}$

The geometric definition of resistance is

$R = \rho\dfrac{l}{A}$

where $\rho$ is the resistivity of the material, $l$ and $A$ are the length and cross-sectional area, respectively.

$A = \rho\dfrac{l}{R}$

$A = \rho\dfrac{l\timesI}{V}$

Since the wire is assumed to have a circular cross-section, its area is given by

$A = \pi\dfrac{d^2}{4}$ where $d$ is the diameter.

$\pi\dfrac{d^2}{4} = \rho\dfrac{l\timesI}{V}$

$d = \sqrt{\dfrac{4\rho l I}{\pi\times V}}$

Resistivity of copper = $1.68\times10^{-8}$ . With these and other given values,

$d = \sqrt{\dfrac{4\times1.68\times10^{-8}\times1.5\times290}{3.14\times 0.55}}$

$d = \sqrt{1128.43\times10^{-8}}$

$d = 33.6\times10^{-4} \text{ m}$

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3 years ago

Heating food under a heat lamp is an example of heat transfer by

Tcecarenko [31]

<span>Heating food under a heat lamp is an example of heat transfer by <span>Radiation</span></span>

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3 years ago

A child whose weight is 287 N slides down a 7.20 m playground slide that makes an angle of 31.0Â° with the horizontal. The coeff

natulia [17]

Answer:

a

$H =212.6 \ J$

b

$v = 7.647 \ m/s$

Explanation:

From the question we are told that

The child's weight is $W_c = 287 \ N$

The length of the sliding surface of the playground is $L = 7.20 \ m$

The coefficient of friction is $\mu = 0.120$

The angle is $\theta = 31.0 ^o$

The initial speed is $u = 0.559 \ m/s$

Generally the normal force acting on the child is mathematically represented as

=> $N = mg * cos \theta$

Note $m * g = W_c$

Generally the frictional force between the slide and the child is

$F_f = \mu * mg * cos \theta$

Generally the resultant force acting on the child due to her weight and the frictional force is mathematically represented as

$F =m* g sin(\theta) - F_f$

Here F is the resultant force and it is represented as $F = ma$

=> $ma = m* g sin(31.0) - \mu * mg * cos (31.0)$

=> $a = g sin(31.0)- \mu * g * cos (31.0)$

=> $a = 9.8 * sin(31.0) - 0.120 * 9.8 * cos (31.0)$

=> $a = 4.039 \ m/s^2$

So

$F_f = 0.120 * 287 * cos (31.0)$

=> $F_f = 29.52 \ N$

Generally the heat energy generated by the frictional force which equivalent tot the workdone by the frictional force is mathematically represented as

$H = F_f * L$

=> $H = 29.52 * 7.2$

=> $H =212.6 \ J$

Generally from kinematic equation we have that

$v^2 = u^2 + 2as$

=> $v^2 = 0.559^2 + 2 * 4.039 * 7.2$

=> $v = \sqrt{0.559^2 + 2 * 4.039 * 7.2}$

=> $v = 7.647 \ m/s$

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3 years ago

What is the volume of a storage tank which will hold 3200kg of petrol?

otez555 [7]

Answer:

The volume of 3200 kg of petrol is 4 m^3.

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3 years ago

When momentum is conserved it is called _____. (multiple choice)

Klio2033 [76]

Answer:

Based off the word "conserved" I would say

A. Conservation of Momentum.

Explanation:

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3 years ago