If the lights are off in a room and there are no windows, why do most objects appear black?

Results of attitude research with twins has revealed

Tamiku [17]

Answer and explanation;

According to twin studies attitudes may be genetically based, research has supported that Identical twins are more likely to share similar attitudes. Attitudes change as the result of behavior and not the other way around

Genetic factors may influence general dispositions and condition-ability that may influence formation of more specific attitudes. Controlled twin studies in US and Sweden reveal that identical twins share more similar attitudes than fraternal twins.

8 0

4 years ago

What is the magnitude of the electric force of attraction between an iron nucleus (q=+26e) and its innermost electron if the dis

iris [78.8K]

Answer:

The magnitude of the force on an electron is 0.069 N.

Explanation:

Given that,

Distance between 1.70 A from the plutonium nucleus, $d=1.5\times 10^{-12}\ m$

The number of electron in iron nucleus is +26e.

To find,

The magnitude of the force between an iron nucleus.

Solution,

Total charge in the plutonium nucleus is, $q=26\times 1.6\times 10^{-19}=4.16\times 10^{-18}\ C$ . The electric force between charges is given by :

$F=\dfrac{kq^2}{d^2}$

$F=\dfrac{9\times 10^9\times (4.16\times 10^{-18})^2}{(1.5\times 10^{-12})^2}$

F = 0.069 N

So, the magnitude of the force on an electron is 0.069 N. Hence, this is the required solution.

4 0

3 years ago

A centrifugal pump discharges 300 gpm against a head of 55 ft when the speed is 1500 rpm. The diameter of the impeller is 15.5 i

Ksivusya [100]

Answer: Question 1: Efficiency is 0.6944

Question 2: speed of similar pump is 2067rpm

Explanation:

Question 1:

Flow rate of pump 1 (Q1) = 300gpm

Flow rate of pump 2 (Q2) = 400gpm

Head of pump (H)= 55ft

Speed of pump1 (v1)= 1500rpm

Speed of pump2(v2) = ?

Diameter of impeller in pump 1= 15.5in = 0.3937m

Diameter of impeller in pump 2= 15in = 0.381

B.H.P= 6.0

Assuming cold water, S.G = 1.0

eff= (H x Q x S.G)/ 3960 x B.H.P

= (55x 300x 1)/3960x 6

= 0.6944

Question 2:

Q = A x V. (1)

A1 x v1 = A2 x V2. (2)

Since A1 = A2 = A ( since they are geometrically similar

A = Q1/V1 = Q2/V2. (3)

V1(m/s) = r x 2π x N(rpm)/60

= (0.3937x 2 x π x 1500)/2x 60

= 30.925m/s

Using equation (3)

V2 = (400 x 30.925)/300

= 41.2335m/s

To rpm:

N(rpm) = (60 x V(m/s))/2 x π x r

= (60 x 41.2335)/ 2× π × 0.1905

= 2067rpm.

6 0

3 years ago

A body with an initial velocity of 10m/s has an acceleration of 8m/s^2. Determine graphically the velocity after 5 seconds, &amp

Pie

Answer:

From the graph, at t = 5 seconds, the velocity = 50 m/s as shown also in the above table

Please find attached the graph

Explanation:

The initial velocity of the body = m/s

The acceleration of the body = 8 m/s²

The velocity after 5 seconds can be determined graphically and by calculation as follows;

Graphically, we have the data points which can be found by the straight line relation v = u + a×t,

Where ,

a = The slope = 8 m/s²

u = 10 m/s = The y-intercept

Which gives;

v = 10 + 8 × t

The following data can be calculated for various time t;

Time, t Velocity , v

0, 10

1, 18

2, 26

3, 34

4, 42

5, 50

6, 58

From the graph, at t = 5 seconds, the velocity = 50 m/s as shown also in the above table

Please find attached the graph

By calculation, we have;

v = u + a×t

Where;

v = The final velocity

u = The initial velocity = 10 m/s

a = The acceleration = 8 m/s²

t = The time = 5 seconds

v = 10 + 5× 8 = 50 m/s.

6 0

3 years ago

A pendulum consists of a 0.3 kg mass at the end of a string. The pendulum is raised to a height of 0.26 m and released. When the

Debora [2.8K]

The total energy of the Pendulum-Earth system is equal to 1.54416 Joules.

<u>Given the following data:</u>

Mass = 0.3 kg

Height = 0.26 meter.

Velocity = 2.28 m/s.

<u>Scientific data:</u>

Acceleration due to gravity on Earth = 9.8 $m/s^2$

To calculate the total energy of the Pendulum-Earth system:

<h3>How to calculate total energy.</h3>

The total energy possessed by this Pendulum-Earth system is equal to the sum of both the potential energy and kinetic energy at its lowest point.

Mathematically, the total energy is given by this formula:

$E = mgh + \frac{1}{2} mv^2$

Substituting the given parameters into the formula, we have;

$E = 0.3 \times 9.8 \times 0.26 + \frac{1}{2}\times 0.3 \times 2.28^2\\\\E=0.7644+0.77976$

E = 1.54416 Joules.

Read more on kinetic energy here: brainly.com/question/17081653

6 0

2 years ago