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Radda [10]
3 years ago
5

An airplane flies in a loop (a circular path in a vertical plane) of radius 200 m . The pilot's head always points toward the ce

nter of the loop. The speed of the airplane is not constant; the airplane goes slowest at the top of the loop and fastest at the bottom
(a) What is the speed of the airplane at the top of the loop, where the pilot feels weightless?
(b) What is the apparent weight of the pilot at the bottom of the loop, where the speed of the air-plane is 280 km/h? His true weight is 700 N.
Physics
1 answer:
Naya [18.7K]3 years ago
8 0

Answer:

Explanation:

a ) for the pilot to feel weightless , his weight will provide the centripetal force . The reaction force from airplane will be zero.

mg = mv² / r

g = v²/r

v² = gr

= 9.8 x 200

v = 44.27 m / s .

b )

v = 280 km / h

v = 77.77 m /s

If R be the reaction force of floor of airplane on him

R - mg = mv² / r

R = mg + m v² / r

= 700 + 70 x  77.77² / 200  ( m = mg / g = 700/ 10 = 70 )

= 700 + 2116.86

= 2816.86  N .

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Photoelectric effect:
Lynna [10]

Answer:

A. K = 0.546 eV

B. cooper and iron will not emit electrons

Explanation:

A. This is a problem about photoelectric effect. Then you have the following equation:

K=h\nu-\Phi=h\frac{c}{\lambda} -\Phi   (1)

K: kinetic energy of the ejected electron

Ф: Work function of the metal = 2.48eV

h: Planck constant = 4.136*10^{-15} eV.s

λ: wavelength of light = 410nm - 750nm

c: speed of light = 3*10^8 m/s

As you can see in the equation (1), higher the wavelength, lower the kinetic energy. Then, the maximum kinetic energy is obtained with the lower wavelength (410nm). Thus, you replace the values of all variables :

K=(4.136*10^{-15}eV)\frac{3*10^8m/s}{410*10^{-9}m}-2.48eV\\\\K=0.546eV

B. First you calculate the energy of the photon with wavelengths of 410nm and 750nm

E_1=(4.136*10^{-15}eV)\frac{3*10^{8}m/s}{410*10^{-9}m}=3.02eV\\\\E_2=(4.13610^{-15}eV)\frac{3*10^{8}m/s}{750*10^{-9}m}=1.6544eV

You compare the energies E1 and E2 with the work functions of the metals and you can conclude:

sodium = 2.3eV < E1

cesium = 2.1 eV < E1

cooper = 4.7eV > E1 (this metal will not emit electrons)

iron = 4.5eV > E1 (this metal will not emit electrons)

5 0
3 years ago
A block moves along a table at a constant velocity and then rolls off the edge of the table. The forces that should be included
Alla [95]

Answer:

Gravity

Explanation:

When the ball is falling to the ground, there is only one force- gravity. In some cases, there may be air resistance, but that seems to be neglected here.

Normal force:

Cannot be included. Normal force is only applicable when object is on a surface, and it acts perpendicular to the surface. Since the ball is falling, there is no surface, and therefore no normal force. This question gives you unnecessary information, designed to trick you. Please remember when normal force is applicable.

Friction force:

Also only applicable when object is moving, and is on the table. Friction only applies when there is an applied force. There is no applied force when the ball is falling, so therefore no friction force.

Force of fall:

First of all, what is this? There is nothing called force of fall.

Gravity:

This is the only one that applies. Just draw a vector arrow from the bottom of the ball and label it mg (acceleration due to gravity).

3 0
3 years ago
The speed of sound in water is 1,492 m/s. A sonar signal is sent straight down from a ship at a point just below the water's sur
ASHA 777 [7]

Answer:

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Explanation:

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2 d =  1492 m/s * 7.5 s

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d = 5595 m

6 0
2 years ago
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jeka94

Answer:

constant velocity unless acted on my an opposite force

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