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Lostsunrise [7]
3 years ago
8

A student librarian lifts a 2.2 kg book from the floor to a height of 1.25 m. He carries the book 8.0 m to the stacks and places

the book on a shelf that is.35 m above the floor. How much work does he do on the book?
I understand most of it, but I am unsure of what distance to use. Please help? ...?
Physics
2 answers:
Montano1993 [528]3 years ago
5 0
The solution to your problem is as follows:


2.2Kg*9.8m/s = 21.56N 
<span>
21.56N*1.25m = 26.95J </span>


<span>We're only concerned with the work done against gravity, lifting the books to 1.25 meters. the distance walked has no effect on the problem, unless you take into account the wind resistance and the force needed to overcome it. Also, lowering the books onto the shelf doesnt count, because gravity does the work on the books.</span>
german3 years ago
5 0

Answer:

W_{tot}=W_{1}+W_{2}=mgh_{2}=7.55[J]

Explanation:

The work done on an object is the scalar product between force and displacement. So we can write the work:

W=F\cdot d=Fd

In our case F and d are parallels then we have a common product of their magnitudes.

Now, the total work will be the sum these two works:

  1. Work done when the student librarian lifts a 2.2 kg book from the floor to a height of h₁=1.25 m.
  2. Work done when he places the book on a shelf that is h₂=0.35 m above the floor.

Let's recall that the force in this problem is just the weight of the book. F=m*g

  • The first work will be: W_{1}=mgh_{1}. F and h1 are parallels
  • The second work will be:W_{2}=-mg(h_{1}-h_{2}) is negative because the vector force and the vector displacement are anti parallels.

Finally, the total work will be the sum of W₁ and W₂.

W_{tot}=W_{1}+W_{2}=mgh_{2}=2.2*9.81*0.35=7.55[J]

I hope it helps you!

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____________ are used to calculate the distance a continent has moved in a year. a. Space satellites c. Laser beams b. Mirrors d
Law Incorporation [45]
<span> Space satellites, laser beams, mirrors</span> are used to calculate the distance a continent has moved in a year.

Therefore, your correct answer would be "all of the above".
4 0
3 years ago
The x component of vector is -27.3 m and the y component is +43.6 m. (a) What is the magnitude of ? (b) What is the angle betwee
lara [203]

Answer:51.44 units

Explanation:

Given

x component of vector is -27.3\hat{i}

y component of vector is 43.6\hat{j}

so position vector is

r=-27.3\hat{i}+43.6\hat{j}

Magnitude of vector is

|r|=\sqrt{27.3^2+43.6^2}

|r|=\sqrt{2646.25}

|r|=51.44 units

Direction

tan\theta =\frac{43.6}{-27.3}=-1.597

vector is in 2nd quadrant thus

180-\theta =57.94

\theta =122.06^{\circ}

4 0
3 years ago
620 J of heat is added to the cylinder of an engine, which causes the gas inside to expand. As a result, the piston of the engin
Maru [420]

Answer:

<u>400</u> J work is done BY the engine.

The internal energy of the gas is <u>620</u> J

Explanation:

The given information are;

The heat added to the cylinder = 620 J

The force applied by the piston of the engine = 8.0 kN = 8,000 N

The distance over which the force moves (the piston) = 5.0 cm = 0.05 m

The work done (by the engine) = Force × Distance = 8,000 N × 0.05 m = 400 J

The internal energy is the sum of the kinetic and potential energy of the system

Therefore, given that the internal energy, U, is the sum total of the energy in the system

∴ U = The heat supplied to the system = 620 J

Which gives;

<u>400</u> J work is done BY the engine.

The internal energy of the gas is <u>620</u> J.

6 0
3 years ago
Find the mass of a 52.2N bucket.​
Goshia [24]

Answer:

m = 5.22 kg

Explanation:

The force acting on the bucket is 52.2 N.

We need to find the mass of the bucket.

The force acting on the bucket is given by :

F = mg

g is acceleration due to gravity

m is mass

m=\dfrac{F}{g}\\\\m=\dfrac{52.2}{10}\\\\=5.22\ kg

So, the mass of the bucket is 5.22 kg.

3 0
3 years ago
A plucked guitar string produces a sound wave with a wavelength of 0.15 m and a velocity of 10.5 m/s, what is the frequency of t
Leno4ka [110]
We know,
V= f× wavelength
10.5= f×0.15
f=10.5/0.15
f= 70 Hz
8 0
3 years ago
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