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julia-pushkina [17]
4 years ago
7

What mass of a material with density rho is required to make a hollow spherical shell having inner radius r1 and outer radius r2

? (Use any variable or symbol stated above as necessary.)
Physics
1 answer:
satela [25.4K]4 years ago
8 0

Answer:

\frac{4}{3}\rho\pi(r_2^3 - r_1^3)

Explanation:

The volume of the shell is the difference between the volume of the outer sphere and the volume of the inner sphere

V = V_o - V_i = \frac{4}{3}\pi r_2^3 - \frac{4}{3}\pi r_1^3

V = \frac{4}{3}\pi(r_2^3 - r_1^3)

The mass of the shell is the product of the volume and its density

m = V\rho = \frac{4}{3}\rho\pi(r_2^3 - r_1^3)

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A force of attraction would exist between
siniylev [52]

Answer:

A. positively charged object and a negatively charged object.

3 0
4 years ago
‏Explain how an electron emitted by the photoelectric effect can have kinetic energy less than threshold energy ?
xenn [34]

Answer:

the photons (quanta of light) collide with the electrons, these electrons have to overcome the threshold energy that is the energy of union with the metal, and the energy that remains is converted to kinetic energy.

          K = E - Ф

Explanation:

The photoelectric effect is the emission of electrons from the surface of a metal.

This was correctly explained by Einstein, in his explanation the energy of the photons (quanta of light) collide with the electrons, these electrons have to overcome the threshold energy that is the energy of union with the metal, and the energy that remains is converted to kinetic energy.

          E = hf

          E = K + Ф

          K = E - Ф

The energy of the photons is given by the Planck relation E = hf and according to Einstein the number of joints must be added

            E = n hf

Therefore, depending on the value of this energy, the emitted electrons can have energy from zero onwards.

4 0
3 years ago
Two identical soccer balls are rolled toward each other. What will be true after they collide headon? (2 points)
elixir [45]

Complete Question:

Two identical soccer balls are rolled toward each other. What will be true after they collide headon?

Group of answer choices.

A. they will both stop rolling immediately after they collide head–on.

B. One ball will stop rolling and the other will roll backward at a slower speed.

C. They will both roll back at the same speed they had before the collision

D.They will both roll to the side at a faster speed after the collision

Answer:

C. They will both roll back at the same speed they had before the collision

Explanation:

Newton's Third Law of Motion which states that, for every action there is an equal but opposite reaction.

This ultimately implies that, in every interaction, there is a pair of forces acting on the two interacting objects.

In this scenario, two identical soccer balls are rolled toward each other. Thus, after they collide headon, they will both roll back at the same speed they had before the collision in accordance with Newton’s Third Law of Motion.

Additionally, The law of conservation of momentum states that the total linear momentum of any closed system would always remain constant with respect to time.

This ultimately implies that, if the two identical soccer balls exert forces only on each other, their total momentum is conserved

5 0
3 years ago
A small first-aid kit is dropped by a rock climber who is descending steadily at 1.3 m/s. After 2.5 s, what is the velocity of t
Artyom0805 [142]

Answer:

D = 30.625 m

Explanation:

given,

Speed of the climber = 1.3 m/s

time = 2.5 s

acceleration due to gravity = 9.8 m/s²

initial speed of the kit = 1.3 m/s

velocity of the kit after 2.5 s

using equation of motion

v = u + a t

v = 1.3 + 9.8 x 2.5

v = 25.8 m/s

distance travel by the kit in 2.5 s

v² = u² + 2 g h

25.8² = 1.3² + 2 x 9.8 x h

19.6 h = 663.95

h = 33.875 m

distance travel by the rock climber in 2.5 s

distance = speed of climber x time

h' = 1.3 x 2.5

h' = 3.25 m

Distance between kit and rock climber

D = h - h'

D = 33.875 - 3.25

D = 30.625 m

The kit is 30.625 m below climber.

8 0
3 years ago
Car A hits car B (initially at rest and of equal mass) from behind while going 15 m/s Immediately after the collision, car B mov
Mamont248 [21]

Given :

Initial speed of car A is 15 m/s and initial speed of car B is zero.

Final speed of car A is zero and final speed of car B is 10 m/s.

To Find :

What fraction of the initial kinetic energy is lost in the collision.

Solution :

Initial kinetic energy is :

K.E_i = \dfrac{15^2m}{2} + 0\\\\K.E_i = \dfrac{225 m}{2}

Final kinetic energy is :

K.E_f = \dfrac{10^2m}{2} + 0\\\\K.E_f = \dfrac{100m}{2}

Now, fraction of initial kinetic energy loss is :

Loss = \dfrac{\dfrac{225m}{2}-\dfrac{100m}{2}}{\dfrac{100m}{2}}\\\\Loss = \dfrac{125}{100}\\\\Loss = 1.25

Therefore, fraction of initial kinetic energy loss in the collision is 1.25 .

6 0
3 years ago
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