The imaginary line from the tip of the football to the football to the sideline is called

Vera and her three sisters received the same amount of money to go to the school festival. Each girl spent $12. Afterward, the g

rodikova [14]

Answer:

$18

Explanation:

Each of the was qiven $18

All together =24

24 divide it by 4 (because there were 4 people there)

= 6 (6+6+6+6)

= 24

=6+12=18

.Hence each of them was given $18

7 0

1 year ago

What is the requirement for the photoelectric effect? Select one: a. The incident light must have enough intensity b. The incide

Softa [21]

Answer:

c. The incident light must have at least as much energy as the electron work function

Explanation:

In photoelectric effect, electrons are emitted from a metal surface when a light ray or photon strikes it. An electron either absorbs one whole photon or it absorbs none. After absorbing a photon, an electron either leaves the surface of metal or dissipate its energy within the metal in such a short time interval that it has almost no chance to absorb a second photon. An increase in intensity of light source simply increase the number of photons and thus, the number of electrons, but the energy of electron remains same. However, increase in frequency of light increases the energy of photons and hence, the

energy of electrons too.

Therefore, the energy of photon decides whether the electron shall be emitted or not. The minimum energy required to eject an electron from the metal surface, i.e. to overcome the binding force of the nucleus is called ‘Work Function’

Hence, the correct option is:

<u>c. The incident light must have at least as much energy as the electron work function</u>

3 0

2 years ago

A small cork with an excess charge of +6.0µC is placed 0.12 m from another cork, which carries a charge of -4.3µC.

Volgvan

A) 16.1 N

The magnitude of the electric force between the corks is given by Coulomb's law:

$F=k\frac{q_1 q_2}{r^2}$

where

k is the Coulomb's constant

$q_1 = 6.0 \mu C=6.0 \cdot 10^{-6} C$ is the magnitude of the charge on the first cork

$q_2 = 4.3 \mu C = 4.3 \cdot 10^{-6}C$ is the magnitude of the charge of the second cork

r = 0.12 m is the separation between the two corks

Substituting numbers into the formula, we find

$F=(9\cdot 10^9 N m^2 C^{-2} )\frac{(6.0\cdot 10^{-6}C)(4.3\cdot 10^{-6} C)}{(0.12 m)^2}=16.1 N$

B) Attractive

According to Coulomb's law, the direction of the electric force between two charged objects depends on the sign of the charge of the two objects.

In particular, we have:

- if the two objects have charges with same sign (e.g. positive-positive or negative-negative), the force is repulsive

- if the two objects have charges with opposite sign (e.g. positive-negative), the force is attractive

In this problem, we have

Cork 1 has a positive charge

Cork 2 has a negative charge

So, the force between them is attractive.

C) $2.69\cdot 10^{13}$

The net charge of the negative cork is

$q_2 = -4.3 \cdot 10^{-6}C$

We know that the charge of a single electron is

$e=-1.6\cdot 10^{-19}C$

The net charge on the negative cork is due to the presence of N excess electrons, so we can write

$q_2 = Ne$

and solving for N, we find the number of excess electrons:

$N=\frac{q_2}{e}=\frac{-4.3\cdot 10^{-6} C}{-1.6\cdot 10^{-19} C}=2.69\cdot 10^{13}$

D) $3.75\cdot 10^{13}$

The net charge on the positive cork is

$q_1 = +6.0\cdot 10^{-6}C$

We know that the charge of a single electron is

$e=-1.6\cdot 10^{-19}C$

The net charge on the positive cork is due to the "absence" of N excess electrons, so we can write

$q_1 = -Ne$

and solving for N, we find the number of electrons lost by the cork:

$N=-\frac{q_1}{e}=-\frac{+6.0\cdot 10^{-6} C}{-1.6\cdot 10^{-19} C}=3.75\cdot 10^{13}$

6 0

2 years ago

An asteroid has a radius of 110,000 m

nydimaria [60]

Answer: M = 6.13 × 10^18 kg

Explanation:

g = GM/r2,

Where

The mass M of the asteroid = ?

The radius r = 110000 m

g = 0.0338 m/s^2

G is the gravitational constant.

SI units its value is approximately 6.674×10^−11m3⋅kg−1⋅s−2

Using the formula

g = GM/r2

Cross multiply

GM = gr^2

6.674×10^-11M = 0.0338 × 110000^2

M = 408×10^6/6.674×10^-11

M = 6.13 × 10^18 kg

7 0

2 years ago

A 1.80-m-tall person stands 3.50 m from a convex mirror and notices that he looks precisely half as tall as he does in a plane m

svlad2 [7]

Answer:

Explanation:

Given:

height of the object $h_o=1.90m$

height of the image $h_i=\frac{h_o}{2}\\=h_i=\frac{1.80}{2}=0.90m$

object distance $d_o=3.50m$

we know that: $\frac{h_i}{h_o}=\frac{-d_i}{d_o}\\\\=d_i=\frac{-h_i}{h_o}\times d_o\\\\=-\frac{0.90}{1.80}\times (3.50)=-1.75m$

image $d_i=-1.75m$

According to lens formular:

$\frac{1}{f}=\frac{1}{d_o}+\frac{1}{d_i}\\\\=\frac{1}{3.50}+-\frac{1}{1.75}\\\\f=-3.5$

focal length= $\frac{radius}{2}\\\\radius=2\times f\\=2\times 3.5=7m$

5 0

2 years ago