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Vikentia [17]
3 years ago
7

An empty office chair is at rest on a floor. Consider the following forces:. 1. A downward force due to gravity;. 2. An upward forc

e exerted by the floor; and. 3. A net downward force exerted by the air. Which force(s) act on the office chair?. 1. None of the forces act on the chair since. it is at rest. 2. All three forces. 3. 1 only. 4. 1 and 2 only. 5. 2 and 3 only.
Physics
1 answer:
Ghella [55]3 years ago
7 0
The answer is:

<span> 4. 1 and 2 only.</span>
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A block of wood is floating in water; it is depressed slightly and then released to oscillate up and down. Assume that the top a
Marysya12 [62]

Explanation:

Equilibrium position in y direction:

W = Fb (Weight of the block is equal to buoyant force)

m*g = V*p*g

V under water = A*h

hence,

m = A*h*p

Using Newton 2nd Law

-m*\frac{d^2y}{dt^2} = Fb - W\\\\-m*\frac{d^2y}{dt^2} = p*g*(h+y)*A - A*h*p*g\\\\-A*h*p*\frac{d^2y}{dt^2} = y *p*A*g\\\\\frac{d^2y}{dt^2} + \frac{g}{h} * y =0

Hence, T time period

T = 2*pi*sqrt ( h / g )

4 0
4 years ago
Some of the highest tides in the world occur in the Bay of Fundy on the Atlantic Coast of Canada. At Hopewell Cape the water dep
Nady [450]

Answer:

(a) 1.939 m/h

(b) 0.926 m/h

(c) -0.315 m/h

(d) -1.21 m/h

Explanation:

Here, we have the water depth given by the function of time;

D(t) = 7 + 5·cos[0.503(t-6.75)]

Therefore, to find the velocity of the depth displacement with time, we differentiate the given expression with respect to time as follows;

D'(t) = \frac{d(7 + 5\cdot cos[0.503(t-6.75)])}{dt}

= 5×(-sin(0.503(t-6.75))×0.503

= -2.515×(-sin(0.503(t-6.75))

= -2.515×(-sin(0.503×t-3.395))

Therefore we have;

(a) at 5:00 AM = 5 -  0:00 = 5

D'(5) =  -2.515×(-sin(0.503×5-3.395)) = 1.939 m/h

(b) at 6:00 AM = 6 -  0:00 = 6

D'(5) =  -2.515×(-sin(0.503×6-3.395)) = 0.926 m/h

(c) at 7:00 AM = 7 -  0:00 = 7

D'(5) =  -2.515×(-sin(0.503×7-3.395)) = -0.315 m/h

(d) at Noon 12:00 PM = 12 -  0:00 = 12

D'(5) =  -2.515×(-sin(0.503×12-3.395)) = -1.21 m/h.

4 0
3 years ago
What are the overall problems with hydrogen energy
OlgaM077 [116]

Expensive: Hydrogen gas actually takes a considerable measure of work to free if from different components. If it were basic and simple to separate, everybody would be utilizing it. It’s now being utilized to power some hybrid vehicles, yet right now it is not a reasonable type of fuel for everybody, mainly because it’s pricey and it’s difficult to get it from place to place. Until research and innovation goes far enough to make this a simpler and cheaper task, hydrogen will likely be something that only the rich can afford.Not Enough Hydrogen Fuel Stations: As you likely know, it’s very difficult to change “the way things are.” As difficult as hydrogen is to create and transport, it gets to be considerably pricier when you consider attempting to utilize it to supplant fuel. There is no current framework set up to hydrogen as the primary fuel for the normal driver. Service stations and vehicles themselves would all must be changed in order to use hydrogen, which can take a lot of time and money to do. It doesn’t seem cost efficient to change from the norm.Safety Concerns: Hydrogen in itself has a lot of power behind it. Though it is less dangerous than gasoline, it’s profoundly flammable and constantly in the news for the potential dangers connected with it. Unlike gas, hydrogen has no smell. Sensors must be used to detect a leak.

7 0
4 years ago
(A) how much work is done when you push a crate horizontally with 100 N across a 10-m factory floor?
Mila [183]

Answer:

A) 1000 joules

Explanation:

In general work is given by the equation:

W=\intop_{a}^{b}\overrightarrow{F}\cdot d\overrightarrow{s} (1)

A) With \overrightarrow{s} the displacement and \overrightarrow{F} the force applied, because the force and the displacement are parallel (the crate is pushed horizontally) \overrightarrow{F}\cdot d\overrightarrow{s} is simply F\,ds, and because the path is a straight line and the force is constant work is:

W=FS (2),

W=(100)(10)=1000\,J

B) The work-energy theorem says that the total work on a body is equal to the change on kinetic energy:

W_{tot}=\varDelta K (3)

The total work on the crate is the work done by the push and plus the work of the friction W_{tot}=W + W_{f} (4) , as (A) because forces are parallel to the displacement W= FS (5) and W_{f}=-fS (6), the due friction always has negative sign because is opposite to the displacement, using (6), (5) and (4) on (3):

FS-fS=\varDelta K (3)

1000-(70)(10)=300\,J

C) The energy is lost by friction, so the amount of energy turned into heat is the work the friction does:

Q=fS=(70)(100)=700\,J (3)

6 0
4 years ago
I am Pushing down at a 20
s344n2d4d5 [400]

Answer:

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Explanation:

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7 0
3 years ago
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