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sasho [114]
4 years ago
10

A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.79

of her regular weight.
(a) Calculate the magnitude of the acceleration of the elevator.
(b) Find the direction of the acceleration.
Physics
1 answer:
Nataly [62]4 years ago
8 0

Answer:

Part a)

a = 2.06 m/s^2

Part b)

Lift is moving downwards as it is coming with negative sign

Explanation:

As we know that the reading of the scale is equal to the normal force on the woman

So we will have

F_n - mg = ma

here we know that

F_n = 0.79 mg

so we will have

0.79 mg - mg = ma

a = -2.06 m/s^2

Part a)

magnitude of the acceleration of the lift is given as

a = 2.06 m/s^2

Part b)

Lift is moving downwards as it is coming with negative sign

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Answer:

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The structure of carpet's surface is as shown. Thus it shows large amount of diffuse reflection.

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How do molecules at warm temperatures differ from molecules at cool temperatures? Question 1 options: At warm temperatures, mole
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7. Water flows trough a horizontal tube of diameter 2.5 cm that is joined to a second horizontal tube of diameter 1.2 cm. The pr
Usimov [2.4K]

To solve this problem it is necessary to apply the concepts related to the continuity of fluids in a pipeline and apply Bernoulli's balance on the given speeds.

Our values are given as

d_1 = 2.5cm \rightarrow r_1=1.25cm=1.25*10^{-2}m

d_2 = 1.2cm \rightarrow r_2 = 0.6cm = 0.6*10^{-2}m

From the continuity equations in pipes we have to

A_1V_1 = A_2 V_2

Where,

A_{1,2} = Cross sectional Area at each section

V_{1,2} = Flow Velocity at each section

Then replacing we have,

(\pi r_1^2) v_1 = (\pi r_2^2) v_2

(1.25*10^{-2})^2 v_1 = ( 0.06*10^{-2})^2 v_2

v_2 = \frac{(1.25*10^{-2})^2 }{0.6*10^{-2})^2} v_1

From Bernoulli equation we have that the change in the pressure is

\Delta P = \frac{1}{2} \rho (v_2^2-v_1^2)

7.3*10^3 = \frac{1}{2} (1000)([ \frac{(1.25*10^{-2})^2 }{0.6*10^{-2})^2} v_1 ]^2-v_1^2)

7300= 8919.01 v_1^2

v_1 = 0.9m/s

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6 0
4 years ago
When a force acts on an object from an angle other than either 0° or 180° to the direction of motion:
inn [45]
You must find the component of the force before calculating
4 0
3 years ago
The common electrical wall receptacle voltage in North America is often referred to as 120 volts AC. One hundred twenty volts is
Vika [28.1K]

Answer:

120 volts is the root mean square (rms) average of the voltage as it varies with time.

Explanation:

A. The average voltage over many weeks of time (false)

Reason: Average AC voltage over one cycle is cycle (from one peak to other) is zero and so over many weeks of time  it is zero.

B. The peak voltage from an AC wall receptacle (false)

Reason: The peak voltage of an AC source in North America is zero.

C. The arithmetic mean of the voltage as it varies with time (false)

Reason: Arithmetic mean AC voltage over one cycle is cycle (from one peak to other) is zero and so over many weeks of time  it is zero.

D.  One-half the peak voltage (false)

Peak voltage =170 Volts

One-half the peak voltage = 85 volts

E. The root mean square (rms) average of the voltage as it varies with time (True)

Reason:

The peak voltage and root mean square voltage are related by:

V_{rms}=\frac{V_{p}}{\sqrt{2} }\\\\V_{rms}=\frac{170}\sqrt{2}V_{rms}\\\\V_{rms}=120 Volts

Average value of voltage over one cycle is zero, so instead of calculating average voltage for AC peak voltage is first squared and the mean is calculated.

5 0
3 years ago
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