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Natasha2012 [34]

3 years ago

14

Why do trains use steel wheels rather than rubber tires? A) Stee

l wheels provide more grip, making it easier to stop a train.
B) Rubber tires don't provide enough friction to allow the train to move.
C) Steel wheels increase friction, thus making it easier to move the load.
D) Steel wheels reduce friction, thus requiring less force to move the load.

2 answers:

Andrej [43]3 years ago

5 0

Steel wheels reduce friction, thus requiring less force to move the load.

kotegsom [21]3 years ago

4 0

D) steel wheels reduce friction, thus requiring less force to move the load. Friction between rubber and steel would be greater than steel and steel. Friction creates heat, which represents a loss of energy (which has to come from somewhere else - likely from the kinetic energy of the train)

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All these are properties except

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Amethyst... because it's silicon dioxide

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3 years ago

Total Internal Reflection

Firdavs [7]

Answer: The light beam will not diffract out of the prism.

Explanation: The angle the light is entering the prism is greater than the critical angle therefore total internal reflection will occur. Hope this helps :)

8 0

3 years ago

Is it possible to have a charge of 5 x 10-20 C? Why?

ruslelena [56]

1) No

2) Yes

3) No

4) Equal and opposite

5) 32400 N

6) Repulsive

7) The electric force is $2.3\cdot 10^{39}$ times bigger than the gravitational force

Explanation:

1)

In nature, the minimum possible charge that an object can have is the charge of the electron, which is called fundamental charge:

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

Electrons are indivisible particles (they cannot be separated), this means that an object can have at least the charge equal to the charge of one electron (in fact, it cannot have a charge less than $e$ , because it would meant that the object has a "fractional number" of electrons).

In this problem, the object has a charge of

$Q=5\cdot 10^{-20}C$

If we compare this value to $e$ , we notice that $Q$ , so no object can have a charge of $Q$ .

2)

As we said in part 1), an object should have an integer number of electrons in order to be charged.

This means that the charge of an object must be an integer multiple of the fundamental charge, so we can write it as:

$Q=ne$

where

Q is the charge of the object

n is an integer multiple

e is the fundamental charge

Here we have

$Q=2.4\cdot 10^{-18}C$

Substituting the value of e, we find n:

$n=\frac{Q}{e}=\frac{2.4\cdot 10^{-18}}{1.6\cdot 10^{-19}}=15$

n is integer, so this value of the charge is possible.

3)

We now do the same procedure for the new object in this part, which has a charge of

$Q=2.0\cdot 10^{-19}C$

Again, the charge on this object can be written as

$Q=ne$

where

n is the number of electrons in the object

Using the value of the fundamental charge,

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

We find:

$n=\frac{Q}{e}=\frac{2.0\cdot 10^{-19}}{1.6\cdot 10^{-19}}=1.25$

n is not integer, so this value of charge is not possible, since an object cannot have a fractional number of electrons.

4)

To solve this part, we use Newton's third law of motion, which states that:

"When an object A exerts a force on an object B (Action force), then object B exerts an equal and opposite force on object A (reaction force)".

In this problem, we have two objects:

- A charge Q

- A charge 5Q

Charge Q exerts an electric force on charge 5Q, and we can call this action force. At the same time, charge 5Q exerts an electric force on charge Q (reaction force), and according to Newton's 3rd law, the two forces are equal and opposite.

5)

The magnitude of the electric force between two single-point charges is

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

where

k is the Coulomb's constant

q1, q2 are the two charges

r is the separation between the two charges

In this problem we have:

$q_1=+4.5\cdot 10^{-6}C$ is charge 1

$q_2=+7.2\cdot 10^{-6}C$ is charge 2

r = 0.30 cm = 0.003 m is the separation

So, the electric force between the two charges is

$F=(9\cdot 10^9)\frac{(4.5\cdot 10^{-6})(7.2\cdot 10^{-6})}{(0.003)^2}=32400 N$

6)

The electric force between two charged objects has direction as follows:

- If the two objects have charges of opposite signs (+ and -), the force between them is attractive

- If the two objects have charges of same sign (++ or --), the force between them is repulsive

In this problem, the two charges are:

$q_1=+4.5\cdot 10^{-6}C$ is charge 1

$q_2=+7.2\cdot 10^{-6}C$ is charge 2

We see that the two charges have same sign: therefore, the force between them is repulsive.

7)

The electric force between the proton and the electron in the atom can be written as

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

where

$q_1 = q_2 = e = 1.6\cdot 10^{-19}C$ is the magnitude of the charge of the proton and of the electron

$r=5.3\cdot 10^{-11} m$ is the separation between them

So the force can be rewritten as

$F_E=\frac{ke^2}{r^2}$

The gravitational force between the proton and the electron can be written as

$F_G=G\frac{m_p m_e}{r^2}$

where

G is the gravitational constant

$m_p = 1.67\cdot 10^{-27}kg$ is the proton mass

$m_e=9.11\cdot 10^{-27}kg$ is the electron mass

Comparing the 2 forces,

$\frac{F_E}{F_G}=\frac{ke^2}{Gm_p m_e}=\frac{(9\cdot 10^9)(1.6\cdot 10^{-19})^2}{(6.67\cdot 10^{-11})(1.67\cdot 10^{-27})(9.11\cdot 10^{-31})}=2.3\cdot 10^{39}$

8 0

3 years ago

Sally and ner pet puagie go everywnere

FrozenT [24]

a)The total distance she walks will be 1100 m.

b)The magnitude and direction of the budgie's path will be 854.4 m at 69.44°.

c)Sally's average speed for the journey will be 2.82 m/sec

d)The average velocity of Sally's budgie willl be 2.19 m/sec North of East.

<h3>What is displacement?</h3>

Displacement is defined as the shortest distance between the two points.

Distance travelled in north direction,d₁ = 8.0 x 10² m

Time elapsed travelled in north direction,t₁ = 5.0 minutes

Distance travelled in east direction,d₂ = 0.30 km = 3.0 × 10² m

Time elapsed travelled in east direction,t₂= 1.5 minutes

The total distance she walks,d =? m

The magnitude and direction of the budgies path will be, D

Sally's average speed for the journey, $\rm S_{avg}$

The average velocity of Sally's budgie, $\rm V_{avg}$

a)

The total distance she walks is found as;

d=d₁+d₂

d=800 m +300 m

d = 1100 m

b)

The magnitude and direction of the budgies path will be;

$\rm D = \sqrt{d_1 ^2 + d_2^2 } \\\\ D = \sqrt{800^2 +300^2 } \\\\ D = 854.4 \ m$

The direction of the displacement is;

$\rm \theta = tan^{-1} \frac{800}{300} \\\\ \theta = tan^{-1}(2.6) \\\\ \theta = 69.44 ^ 0$

c)journey is found as;

Sally's average speed for the

$\rm S_{avg} = \frac{d}{t} \\\\ S_{avg} =\frac{100}{300+900} \\\\ S_{avg} =2.82 \ m/sec$ <em>
</em>

d)

The average velocity of Sally's budgie is found as;

$\rm V_{avg} = \frac{854.4}{300+ 900 } \\\\ V_{avg} = 2.19 \ m/sec$ North of east

Hence, the total distance she walks, the magnitude and direction of the budgie's path, Sally's average speed, and the average velocity of Sally's budgie will be 1100 m,854.4 m at 69.44°,2.82 m/sec, and 2.19 m/sec North of East.

To learn more about displacement refer to the link;

brainly.com/question/10919017

#SPJ1

6 0

2 years ago

A train leaves the station heading west on the tracks . It takes the train 8 seconds to reach 80 miles per hour . It completes t

Virty [35]

Average speed=160/2=80mile/hour

4 0

3 years ago