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2 years ago

15

A car starts at point A from rest. It returns to point A in 30 seconds. The race from start to finish is 1 mile.

1 answer:

SVEN [57.7K]2 years ago

3 0

D the answer you’re looking for is letter d.

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The intensity of a certain siren is 0.060 W/m^2 from a distance of 25 meters. What is the intensity of this siren at a distance

Nady [450]

<h2>The intensity of siren is 0.015 W m⁻²</h2>

Explanation:

The intensity of sound is inversely proportional to the square of distance between source and the observer .

Thus Intensity at a distance 25 m is I₁ ∝ $\frac{1}{r_1^2}$ I

Similarly the intensity at a distance 50 m is I₂ ∝ $\frac{1}{r_2^2}$ II

Dividing II by I , we have

$\frac{I_2}{I_1}$ = $\frac{r_1^2}{r_2^2}$ = $\frac{25^2}{50^2}$ = $\frac{1}{4}$

Thus I₂ = $\frac{1}{4}$ x 0.06 = 0.015 W m⁻²

7 0

3 years ago

Show that the energy of a magnetic dipole m in a magnetic field B is U--m B

Juli2301 [7.4K]

Answer:

showm

Explanation:

Consider a dipole having magnetic moment 'm' is placed in magnetic field $\vec{B}$ then the torque exerted by the field on the dipole is

$\tau = m\times B$

$\tau=mBsin\alpha$

Now to rotate the dipole in the field to its final position the work required to be done is

$U=\int \tau d\alpha$

$U=\int mBsin\alpha d\alpha$

$U= -mBcos\alpha$

$U=-\vec{m\times \vec{B}}$

Minimum energy mB is for the case when m is anti parallel to B.

Minimum energy -mB is for the case when m is parallel to B.

5 0

3 years ago

How does Physics help you as a student?

Sonja [21]

Answer:

The goal of physics is to understand how things work from first principles. ... Courses in physics reveal the mathematical beauty of the universe at scales ranging from subatomic to cosmological. Studying physics strengthens quantitative reasoning and problem solving skills that are valuable in areas beyond physics

8 0

2 years ago

Read 2 more answers

A student is running to catch the campus shuttle bus, which is stopped at the bus stop. The student is runnign at a constant spe

Serggg [28]

Answer:

Part a)

$t = 16.8 s$

$d = 100.8 m$

Part b)

$v_f = 2.86 m/s$

Explanation:

Part a)

Constant speed by which the student will run is given as

$v = 5 m/s$

now after some time if student is going to overtake the position of bus

so here the final positions will be same

so we have

$x_{bus} = x_{student}$

$0 + \frac{1}{2}at^2 + d = v_{student} t$

$\frac{1}{2}(0.170)t^2 + 60 = 5 t$

$0.085 t^2 - 5t + 60 = 0$

so it is

$t = 16.8 s$

So student will run the total distance

$d = vt$

$d = (6)(16.8)$

$d = 100.8 m$

Part b)

Speed of bus when student reach the bus is given as

$v_f = v_i + at$

$v_f = 0 + (0.170)(16.8)$

$v_f = 2.86 m/s$

4 0

3 years ago

Land heats up and cools down quickly because...

chubhunter [2.5K]

I would say it reflects the sun easily. That’s also how we see it :)

6 0

3 years ago