If a substance has an atomic mass of 20 and has an atomic number of 10, how many neutrons does this element have?

An inventor develops a stationary cycling device by which an individual, while pedaling, can convert all of the energy expended

mr Goodwill [35]

Answer:

$Q=94185\ J$

Explanation:

Given:

mass of water, $m=0.3\ kg$

initial temperature of water, $T_i=20^{\circ}C$

final temperature of water, $T_f=95^{\circ}C$

specific heat of water, $c=4186\ J.kg^{-1}.K^{-1}$

<u>Now the amount of heat energy required:</u>

$Q=m.c.\Delta T$

$Q=0.3\times 4186\times (95-20)$

$Q=94185\ J$

Since all of the mechanical energy is being converted into heat, therefore the same amount of mechanical energy is required.

4 0

3 years ago

George walks to a friend's house. He walks 850 meters north before he realizes he walked too far.

anyanavicka [17]

Answer:

Explanation:

In this problem we are expected to calculate the velocity of Georges movements.

Given data

Total distance covered by George= 850+250= 1100 meters

Time taken by George to cover the total distance= 25 seconds

We know that velocity is, v= distance/ time

Therefore substituting our data into the expression for velocity we have

v= 1100/ 25= 44 m/s

Hence the velocity in m/s is 44

7 0

2 years ago

A skateboarder starts from rest and maintains a constant acceleration of 0.50 m/s² for 8.4 s. What is the rider's displacement d

gregori [183]

Answer:

4.2m/s

Explanation:

0.50x8.4=4.2m/s

3 0

2 years ago

Charge g is distributed in a spherically symmetric ball of radius a. (a) Evaluate the average volume charge density p. (b) Now a

nasty-shy [4]

Answer:

Explanation:

The volume of a sphere is:

V = 4/3 * π * a^3

The volume charge density would then be:

p = Q/V

p = 3*Q/(4 * π * a^3)

If the charge density depends on the radius:

p = f(r) = k * r

I integrate the charge density in spherical coordinates. The charge density integrated in the whole volume is equal to total charge.

$Q = \int\limits^{2*\pi}_0\int\limits^\pi_0 \int\limits^r_0 {k * r} \, dr * r*d\theta* r*d\phi$

$Q = k *\int\limits^{2*\pi}_0\int\limits^\pi_0 \int\limits^r_0 {r^3} \, dr * d\theta* d\phi$

$Q = k *\int\limits^{2*\pi}_0\int\limits^\pi_0 {\frac{r^4}{4}} \, d\theta* d\phi$

$Q = k *\int\limits^{2*\pi}_0 {\frac{\pi r^4}{4}} \, d\phi$

$Q = \frac{\pi^2 r^4}{2}}$

Since p = k*r

Q = p*π^2*r^3 / 2

Then:

p(r) = 2*Q / (π^2*r^3)

3 0

2 years ago

A lightning bolt transfers 6.0 coulombs of charge from a cloud to the ground in 2.0 x 10-3 second. what is the average current d

AlladinOne [14]

The current is defined as the amount of charge transferred through a certain point in a certain time interval:
$I= \frac{Q}{\Delta t}$
where
I is the current
Q is the charge
$\Delta t$ is the time interval

For the lightning bolt in our problem, Q=6.0 C and $\Delta t= 2.0 \cdot 10^{-3}s$ , so the average current during the event is
$I= \frac{Q}{\Delta t} = \frac{6.0 C}{2.0 \cdot 10^{-3} s}=3000 A$

4 0

3 years ago