1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Lynna [10]
2 years ago
5

Calculate the average speed of a runner who runs to for 500 meters in 40 second

Physics
1 answer:
siniylev [52]2 years ago
5 0

Answer:

12.5

Explanation:

You might be interested in
A steady current I flows through a wire of radius a. The current density in the wire varies with r as J = kr, where k is a const
grin007 [14]

Answer:

Explanation:

we can consider an element of radius r < a and thickness dr.  and Area of this element is

dA=2\pi r dr

since current density is given

J=kr

then , current through this element will be,

di_{thru}=JdA=(kr)(2\pi\,r\,dr)=2\pi\,kr^2\,dr

integrating on both sides between the appropriate limits,

\int_0^Idi_{thru}=\int_0^a2\pi\,kr^2\,dr&#10;\\\\&#10;I=\frac{2\pi\,ka^3}{3} -------------------------------(1)

Magnetic field can be found by using Ampere's law

\oint{\vec{B}\cdot\,d\vec{l}}=\mu_0\,i_{enc}

for points inside the wire ( r<a)

now, consider a point at a distance 'r' from the center of wire. The appropriate Amperian loop is a circle of radius r.

by applying the Ampere's law, we can write

\oint{\vec{B}_{in}\cdot\,d\vec{l}}=\mu_0\,i_{enc}&#10;

by symmetry \vec{B} will be of uniform magnitude on this loop and it's direction will be tangential to the loop.

Hence,

B_{in}\times2\pi\,l=\mu_0\int_0^r(kr)(2\pi\,r\,dr)=&#10;\\\\2\pi\,B_{in} l=2\pi\mu_0k \frac{r^3}{3}&#10;\\\\B_{in}=\frac{\mu_0kl^2}{3}&#10;

now using equation 1, putting the value of k,

B_{in} = \frac{\mu_{0} l^2 }{3 } \,\,\, \frac{3I}{2 \pi a^3}&#10;\\\\B_{in} = \frac{ \mu_{0} I l^2}{2 \pi a^3}&#10;

B)

now, for points outside the wire ( r>a)

consider a point at a distance 'r' from the center of wire. The appropriate Amperian loop is a circle of radius l.

applying the Ampere's law

\oint{\vec{B}_{out}\cdot\,d\vec{l}}=\mu_0\,i_{enc}&#10;

by symmetry \vec{B} will be of uniform magnitude on this loop and it's direction will be tangential to the loop. Hence

B_{out}\times2\pi\,r=\mu_0\int_0^a(kr)(2\pi\,r\,dr)&#10;\\\\2\pi\,B_{out}r=2\pi\mu_0k\frac{a^3}{3}&#10;\\\\B_{out}=\frac{\mu_0ka^3}{3r}&#10;

again using,equaiton 1,

B_{out}= \mu_0 \frac{a^3}{3r} \times \frac{3 I}{2 \pi a^3}&#10;\\\\B_{out} = \frac{ \mu_{0} I}{2 \pi r}

8 0
3 years ago
What element has 3 valence electrons and 4 energy levels​
Tems11 [23]
Gallium is the answer
6 0
3 years ago
On a sunny summer day, why does a white car with a light-colored interior stay cooler than a black car with a dark-colored inter
Oduvanchick [21]

Answer: Solar radiation reflects off the lighter colours, away from the car, thus keeping the car cool

Explanation: This is because lighter colors reflect a good amount of radiation while darker colors absorb it. Just like, Antarctica hasn't completely melted because it reflects a lot of the heat that is acting upon it. Or, you notice that you get hotter when you wear a black shirt opposed to a white one.

8 0
3 years ago
HELP QUICK PLZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
KIM [24]

Answer:

the answer is c

Explanation:

6 0
3 years ago
Read 2 more answers
A 15x10^-6c charge is placed at the origin and a 9x10^-6C charge is placed on the x-axis at x=1.00m. where, on the x-axis is the
Harlamova29_29 [7]

The Electric field is zero at a distance 2.492 cm from the origin.

Let A be point where the charge 15\times10^-6 C is placed which is the origin.

Let B be the point where the charge 9\times 10^-6 C is placed. Given that B is at a distance 1 cm from the origin.

Both the charges are positive. But charge at origin is greater than that of B. So we can conclude that the point on the x-axis where the electric field = 0 is after B on x - axis.

i.e., at distance 'x' from B.

Using Coulomb's law, \frac{kQ_A^2}{d_A^2} = \frac{kQ_B^2}{d_B^2},

Q_A = 15\times 10^-6 C

Q_B=9\times10^-6C

d_A = 1+x cm

d_B=x cm

k is the Coulomb's law constant.

On substituting the values into the above equation, we get,

\frac{(15\times10^-6)^2}{(1+x)^2} =\frac{(9\times10^-6)^2}{x^2}

Taking square roots on both sides and simplifying and solving for x, we get,

1.67x = 1+x

Therefore, x = 1.492 cm

Hence the electric field is zero at a distance 1+1.492 = 2.492 cm from the origin.

Learn more about Electric fields and Coulomb's Law at brainly.com/question/506926

#SPJ4

3 0
1 year ago
Other questions:
  • Platinum has a density of 21 g/cm3. a platinum ring is placed in a graduated cylinder that contains water. the water level rises
    13·2 answers
  • If I put one hand in hot tap water and the other in cold tap water then both in the same warm tap water what will happen
    14·1 answer
  • Why do astronauts appear to move in slow motion in space?
    13·1 answer
  • What type of air mass brings a hurricane?
    12·1 answer
  • A wave is traveling through a string and six waves pass a point in three seconds what is the frequency of the wave
    8·1 answer
  • Which index of refraction represents the most optically dense material?
    14·2 answers
  • The difference between relational and reactive aggression is that relational aggression is ______, whereas reactive aggression i
    13·1 answer
  • The second-order bright fringe in a single-slit diffraction pattern is 1.35 mm from the center of the central maximum. The scree
    15·1 answer
  • Full moon is located______
    9·2 answers
  • 500 J of work is used to decrease the angular velocity of a disk from 65 rad/s to 52 rad/s.What is the rotational inertia of the
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!