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kvasek [131]
3 years ago
12

A bus travels 30km in 1/2h. What is it's average speed in km/h

Physics
1 answer:
Vadim26 [7]3 years ago
5 0
If a bus travels 30 km in 1/2 hr, then in one hr, he can travel twice the distance.
30*2=60 km

Final answer: 60 km per hr
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The magnetic field at the center of a 1.40-cm-diameter loop is 2.50 mT . PART A) What is the current in the loop?
NISA [10]

Explanation:

It is given that,

Diameter of loop, d = 1.4 cm

Radius of loop, r = 0.7 cm = 0.007 m

Magnetic field, B=2.5\ mT=2.5\times 10^{-3}\ T

(A) Magnetic field of a current loop is given by :

B=\dfrac{\mu_oI}{2r}

I is the current in the loop

I=\dfrac{2Br}{\mu_o}

I=\dfrac{2\times 2.5\times 10^{-3}\times 0.007}{4\pi \times 10^{-7}}

I = 27.85 A

(B) Magnetic field at a distance r from a wire is given by :

B=\dfrac{\mu_o I}{2\pi r}

r=\dfrac{\mu_o I}{2\pi B}

r=\dfrac{4\pi \times 10^{-7}\times 27.85}{2\pi \times 2.5\times 10^{-3}}

r = 0.00222 m

r=2.2\times 10^{-3}\ m

Hence, this is the required solution.

3 0
3 years ago
Calculate the distance traveled by a projectile as a function of launch angle. Compare the distances for two projectiles launche
DaniilM [7]

Answer:

R = x_{max} = \frac{v^2\sin(2\theta)}{g}\\\frac{R_1}{R_2} = \frac{\sin(2\theta_1}{\sin(2\theta_2}

Explanation:

Using kinematics equations:

\Delta x = v_{0x}t\\\Delta y = -\frac{1}{2}gt^2+v_{0y}t

Use \Delta y = 0 due to condition of distance traveled.

Solving second equation for time, there are two solutions. t=0 and

t=\frac{2v_{0y}}{g}

Use the expression in the first equation to have

R = \frac{2v^2 \cos\theta\sin\theta}{g}

Using trigonometric identities, you have the answer of the distance.

By doing the ratio for two different angles, you have the second answer. Due to sine function properties, the distances can be the same to complementary angles. Example, for 20° and 70°, the distance is the same.

5 0
3 years ago
As 390 g of hot milk cools in a mug it transfers 30 000 j of heat to the environment. whats is the temperature change of the mil
Fed [463]
You have to use the specific heat equation. 

Q = cmΔT where Q is the energy, c is specific heat, m is mass, and ΔT is change in temp.

So we can substitute our variables into the equation.

30000J = (390g)(3.9J*g/C)ΔT

Solving for ΔT, we get:

30000J/[(390g)*(3.9J*g/C) = ΔT

ΔT = 19.72386588C

I'm assuming the temperature is C, since it was not specified.

Hope this helps!
8 0
3 years ago
Why is an object's density expressed as a relationship between two units?
vfiekz [6]
Probably for kind of the same reason that speed is expressed as a
relationship between two units.  You know, like miles per hour .

I guess the only reason is because no single unit has been invented
to describe density.

The rate of doing work or using energy would always be expressed
as a relationship between two units ... we would say that the rate of
work is "(so many) joules per second".  But the "watt" was invented,
so we can say "(so many) watts" instead.

So I guess you're right.  Density could be simpler to describe
if we only had a unit for it.  Then we wouldn't have to say "(so many)
grams per cubic centimeter".  We would just say "(so many) (new unit)".

Let's try it out:
 
"Uhhh, pardon me Professor . . . I've been working late in the lab,
and I believe I've identified a new substance, hitherto unknown to
the scientific community, and totally unexpected.  In its pure form,
the substance appears to be pink, it smells like butterscotch, and
its density is approximately 27.4 Brianas.  I think it's time we published
these findings ... with your name as lead investigator, of course."

I like it !
5 0
4 years ago
Estimate the number of times the earth will rotate on its axis during a human’s lifetime
Fudgin [204]

Here we have to calculate  the number of rotations made by earth around its own axis in the entire life time of a human being.

The average human life is 50 years .

Each year is 365.5 days

Hence 50 years =50 *365.5 days

                 =18,275 days

The earth rotates around its own axis in 23 hours 56 minutes and 4 second which is approximately equal to 24 hours or one days.

Hence one rotation takes one days.

⇒18,275 days =18,275 rotations

Hence the total number of rotations made by earth around its own axis in the life time of a average human life time will be 18,275 times

7 0
3 years ago
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