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madreJ [45]
4 years ago
13

What kind of mirrors are typically used for security purposes?

Physics
1 answer:
fredd [130]4 years ago
6 0

Answer:

CONVEX

Explanation:

BECOZ IT HELPS TO GET A WIDER VIEW

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Two Earth satellites, A and B, each of mass m, are to be launched into circular orbits about Earth’s center. Satellite A is to o
Vera_Pavlovna [14]

Answer:

Explanation:

Orbital radius of satellite A , Ra = 6370 + 6370 = 12740 km

Orbital radius of satellite B , Rb = 6370 + 19110 = 25480 km

Orbital potential energy of a satellite = - GMm / r where G is gravitational constant , M is mass of the earth and m is mass of the satellite

Orbital potential energy of a satellite A = - GMm / Ra

Orbital potential energy of a satellite B = - GMm / Rb

PE of satellite B /PE of satellite A

=  Ra / Rb

= 12740 / 25480

= 1 / 2

b ) Kinetic energy of a satellite is half the potential energy with positive value , so ratio of their kinetic energy will also be same

KE of satellite B /KE of satellite A

= 1 / 2

c ) Total energy will be as follows

Total energy = - PE + KE

- P E + PE/2

= - PE /2

Total energy of satellite B / Total energy of A

= 1 / 2

Satellite B will have greater total energy because its negative value is less.

5 0
3 years ago
A bowler throws a bowling ball of radius R = 11 cm down the lane with initial speed v₀ = 7.5 m/s. The ball is thrown in such a w
salantis [7]

Answer:

a) t = 0.74s

b) D = 4.76m

c) Vf = 5.35m/s

Explanation:

The ball starts rolling when Vf = ωf*R.

We know that:

Vf = Vo - a*t

ωf = ωo + α*t

With a sum of forces on the ball:

Ff = m*a

\mu*N = m*a

\mu*m*g = m*a

a=\mu*g=2.9m/s^2

With a sum of torque on the ball:

Ff*R = I*\alpha

\mu*m*g*R = 2/5*m*R^2*\alpha

\alpha=5/2*\mu*g/R=65.9rad/s^2

Replacing both accelerations:

Vo - a*t=\alpha*t*R

7.5 - 2.9*t=65.9*t*0.11

t=0.74s

The distance will be:

D = Vo*t-1/2*a*t^2

D = 4.76m

Final velocity:

Vf=Vo-a*t

Vf=5.35m/s

7 0
3 years ago
The energy band gap of GaAs is 1.4eV. calculate the optimum wavelength of light for photovoltaic generation in a GaAs solar cell
Viktor [21]

Answer:

λ = 8.88 x 10⁻⁷ m = 888 nm

Explanation:

The energy band gap is given as:

Energy Gap = E = 1.4 eV

Converting this to Joules (J)

E = (1.4 eV)(1.6 x 10⁻¹⁹ J/1 eV)

E = 2.24 x 10⁻¹⁹ J

The energy required for photovoltaic generation is given as:

E = hc/λ

where,

h = Plank's Constant = 6.63 x 10⁻³⁴ J.s

c = speed of light = 3 x 10⁸ m/s

λ = wavelength of light = ?

Therefore,

2.24 x 10⁻¹⁹ J = (6.63 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/λ

λ = (6.63 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/(2.24 x 10⁻¹⁹ J)

<u>λ = 8.88 x 10⁻⁷ m = 888 nm</u>

7 0
3 years ago
Sonia's grandfather was not able to see clearly after returning from his walk on a bright sunny day. He was about to hit a chair
Vinil7 [7]

Answer:

Sonia's grandfather was not able to see clearly after returning from his walk on a bright sunny day. He was about to hit a chair when Sonia held him and guided him to the nearby sofa, in sunny environment grandfather's eye is set according to high brightness, his pupils become small to lower the number of light rays entering his eye, when he returned from sunny environment to his house which was having low brightness so the pupils should enlarge to absorb more light to see clearly but due to old age his Ciliary muscle of the eye would have worn out and due to this poor coordination the image was not clear.

4 0
3 years ago
The figure below shows a man in a boat on a lake. The man's mass is 74 kg, and the boat's is 135 kg. The man and boat are initia
vazorg [7]

The velocity of the boat after the package is thrown is 0.36 m/s.

<h3>Final velocity of the boat</h3>

Apply the principle of conservation of linear momentum;

Pi = Pf

where;

  • Pi is initial momentum
  • Pf is final momentum

v(74 + 135) = 15 x 5

v(209) = 75

v = 75/209

v = 0.36 m/s

Thus, the velocity of the boat after the package is thrown is 0.36 m/s.

Learn more about velocity here: brainly.com/question/6504879

#SPJ1

7 0
2 years ago
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