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3 years ago

12

PLZ HELP TIMED TEST

2 answers:

koban [17]3 years ago

8 0

Recycling aluminum products

marysya [2.9K]3 years ago

4 0

Answer:

recycling aluminum products

Explanation:

I I took this test hope this out and on the test I got this correct

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Jack and Jill are maneuvering a 3300 kg boat near a dock. Initially the boat's position is < 2, 0, 3 > m and its speed is

Paraphin [41]

Answer:

The workdone by Jack is $W_{jack} = -1050J$

The workdone by Jill is $W_{Jill} = 0J$

The final velocity is $v = 1.36 m/s$

Explanation:

From the question we are given that

The mass of the boat is $m_b = 3300kg$

The initial position of the boat is $P_i = (2 \r i + 0 \r j + 3\r k)m$

The Final position of the boat is $P_f = (4\r i + 0 \r j + 2\r k )\ m$

The Force exerted by Jack $\r F = (-420\r i + 0 \r j + 210\r k) \ N$

The Force exerted by Jill $\r F_{Jill} =(180 \r i + 0\r j + 360\r k)$

Now to obtain the displacement made we are to subtract the final position from the initial position

$\r P = P_f - P_i$

$= (4\r i + 0\r j + 2 \r k) - (2\r i + 0\r j + 3\r k )$

$= (2\r i + 0\r j -\r k )m$

Now that we have obtained the displacement we can obtain the Workdone

which is mathematically represented as

$W =\r F * \r P$

The amount of workdone by jack would be

$W_{jack} =\r F * \r P$

$= [(-420\r i +0\r j +210\r k)(2\r i + 0\r j - \r k)]$

$= (-420) (2) + (210)(-1)$

$= -840 - 210$

$=-1050J$

The amount of workdone by Jill would be

$W_{Jill} =\r F * \r P$

$= [(180 \r i + 0\r j + 360\r k)(2\r i +0\r j -\r k)]$

$= (180 )(2) +(360)(-1)$

$=0J$

According to work energy theorem the Workdone is equal to the kinetic energy of the boat

$W = K.E = \frac{1}{2} m *[v^2 - (1.1)^2]$

$-1050 = 0.5*3300 [*v^2- (1.1)^2]$

$-1050 = 1650 [v^2 -1.21]$

$0.6363 = v^2 -1.21$

$v^2 = 0.6363+1.21$

$v^2 =1.846$

$v = 1.36\ m/s$

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4 years ago

Why is physics the hardest subject

horrorfan [7]

Physics can demand that you start with a specific result and make general rules. Not reading the text and not solving exercises makes understanding almost impossible. It also involves a lot of math which most people do not like.

3 0

2 years ago

Read 2 more answers

During which phase change will the greatest amount of energy be absorbed by 1 gram of water

diamong [38]

Processes in which matter changes between liquid and gaseous states are vaporization, evaporation, and condensation.

8 0

3 years ago

An object moving due to gravity can be described by the motion equation y=y0+v0t−12gt2, where t is time, y is the height at tha

Lynna [10]

Answer: 6.45 s

Explanation:

We have the following equation:

$y=y_{o}+V_{o}t-\frac{1}{2}gt^{2}$ (1)

Where:

$y=0$ is the height when the rock hits the ground

$y_{o}=75 m$ the height at the edge of the cilff

$V_{o}=20 m/s$ the initial velocity

$g=9.8 m/s^{2}$ acceleration due gravity

$t$ time

$0=75 m+(20 m/s)t-(4.9 m/s^{2})t^{2}$ (2)

Rearranging the equation:

$-(4.9 m/s^{2})t^{2} + (20 m/s)t + 75 m=0$ (3)

At this point we have a quadratic equation of the form $at^{2}+bt+c=0$ , and we have to use the quadratic formula if we want to find $t$ :

$t=\frac{-b\pm\sqrt{b^{2}-4ac}}{2a}$ (4)

Where $a=-4.9$ , $b=20$ , $c=75$

Substituting the known values and choosing the positive result of the equation:

$t=\frac{-20\pm\sqrt{20^{2}-4(-4.9)(75)}}{2(-4.9)}$ (5)

$t=6.453 s$ This is the time it takes to the rock to hit the ground

8 0

3 years ago

A force of 450 N accelerates a box across a frictionless surface at a rate of 15 m/s 2 . What is the mass of the box?

kow [346]

Used Mephyso for the calculation

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4 years ago