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11Alexandr11 [23.1K]
3 years ago
9

Some students want to calculate the work done by friction as an object with unknown mass moves along a straight line on a rough

horizontal surface. The students have a force probe, a meterstick, and a stopwatch. Which of the following will allow lo lake the measurements needed to calculate the work done by friction?
(A) Pulling the block at an unknown constant acceleration with the force probe for a measured time.
(B) Pulling the block at an unknown constant speed with the force probe for a measured time.
(C) Pulling the block at an unknown constant acceleration with the force probe for a measured distance.
(D) Pulling the block at an unknown constant speed with the force probe for a measured distance.
Physics
1 answer:
goblinko [34]3 years ago
3 0

Answer:

(C) Pulling the block at an unknown constant acceleration with the force probe for a measured distance.

Explanation:

As we know that work done is defined by the product of force and displacement

so it is given as

W = F. d

so here in order to find the work done we must know that force and displacement both

so we must have to pull the block with uniform acceleration and then we need to measure the distance to find the work done

so correct answer will be

(C) Pulling the block at an unknown constant acceleration with the force probe for a measured distance.

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Answer:

The answer to the question is

The roller coaster will reach point B with a speed of 14.72 m/s

Explanation:

Considering both kinetic energy KE = 1/2×m×v² and potential energy PE = m×g×h

Where m = mass

g = acceleration due to gravity = 9.81 m/s²

h = starting height of the roller coaster

we have the given variables

h₁ = 36 m,

h₂ = 13 m,

h₃ = 30 m

v₁ = 1.00 m/s

Total energy at point 1 = 0.5·m·v₁² + m·g·h₁

= 0.5 m×1² + m×9.81×36

=353.66·m

Total energy at point 2 = 0.5·m·v₂² + m·g·h₂

= 0.5×m×v₂² + 9.81 × 13 × m = 0.5·m·v₂² + 127.53·m

The total energy at 1 and 2 are not equal due to the frictional force which must be considered

Total energy at point 2 = Total energy at point 1 + work done against friction

Friction work = F×d×cosθ = (\frac{1}{5} × mg)×60×cos 180 = -117.72m

0.5·m·v₂² + 127.53·m = 353.66·m -117.72m

0.5·m·v₂² = 108.41×m

v₂² = 216.82

v₂  =  14.72 m/s

The roller coaster will reach point B with a speed of 14.72 m/s

8 0
3 years ago
A rectangular loop of copper wire of resistance r has width a and length
sergij07 [2.7K]

Answer:

Explanation:

b = b₀ cos ω t

When t = 0 , magnetic field will be b₀ and positive or directed into the page . This is the maximum value of magnetic field. As times goes ahead , magnetic field decreases so magnetic flux decreases . The induced emf or current will be such that it will  opposes this reduction of magnetic field. Hence , current in clockwise direction will be  generated in the coil which will generate magnetic flux into the paper.

In this way  current will be induced  clockwise.

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3 years ago
In unit-vector notation, what is the torque about the origin on a particle located at coordinates (0 m, −3.0 m, 2.0 m) due to fo
irinina [24]

Answer:

The torque about the origin is 2.0Nm\hat{i}-8.0Nm\hat{j}-12.0Nm\hat{k}

Explanation:

Torque \overrightarrow{\tau} is the cross  product between force \overrightarrow{F} and vector position \overrightarrow{r} respect a fixed point (in our case the origin):

\overrightarrow{\tau}=\overrightarrow{r}\times\overrightarrow{F}

There are multiple ways to calculate a cross product but we're going to use most common method, finding the determinant of the matrix:

\overrightarrow{r}\times\overrightarrow{F} =-\left[\begin{array}{ccc} \hat{i} & \hat{j} & \hat{k}\\ F1_{x} & F1_{y} & F1_{z}\\ r_{x} & r_{y} & r_{z}\end{array}\right]

\overrightarrow{r}\times\overrightarrow{F} =-((F1_{y}r_{z}-F1_{z}r_{y})\hat{i}-(F1_{x}r_{z}-F1_{z}r_{x})\hat{j}+(F1_{x}r_{y}-F1_{y}r_{x})\hat{k})

\overrightarrow{r}\times\overrightarrow{F} =-((0(2.0m)-0(-3.0m))\hat{i}-((4.0N)(2.0m)-(0)(0))\hat{j}+((4.0N)(-3.0m)-0(0))\hat{k})

\overrightarrow{r}\times\overrightarrow{F}=-2.0Nm\hat{i}+8.0Nm\hat{j}+12.0Nm\hat{k}=\overrightarrow{\tau}

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2 years ago
A student wants to demonstrate entropy using the songs on her portable music player. What should she do to demonstrate the lowes
antoniya [11.8K]

Answer:  A. play a single song by a single artist

Explanation: Entropy is the measure of randomness or disorder of a system.

A system that has more random distribution is considered to have more entropy and a system with ordered arrangement is considered to have less entropy.

Playing a single song by a single artist has least randomness , and lowest disorder and thus has lowest entropy.

4 0
3 years ago
In a common but dangerous prank, a chair is pulled away as a person is moving downward to sit on it, causing the victim to land
Marina CMI [18]

Answer:

(a) \vec{J}=176.4\frac{kg*m}{s} \hat{j}

(b) F=2125.30N

Explanation:

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\Delta U=\Delta K\\mgh=\frac{mv^2}{2}\\v=\sqrt{2gh}\\v=\sqrt{2(9.8\frac{m}{s^2})(0.40m)}\\v=2.8\frac{m}{s}

This is the initial velocity in the negative y-direction. Impulse is given by:

\vec{J}=\Delta \vec{p}\\\vec{J}=m\vec{v_f}-m\vec{v_i}\\\vec{J}=63kg(0 \hat{j})-63kg(-2.8\frac{m}{s} \hat{j})\\\vec{J}=176.4\frac{kg*m}{s} \hat{j}

(b) The average force is:

F=\frac{J}{\Delta t}\\F=\frac{176.4\frac{kg*m}{s}}{0.083s}\\F=2125.30N

6 0
3 years ago
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