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3 years ago

What is the potential energy of a 3 kg- ball that is on the ground?

1 answer:

4 0

With respect to the ground, the 3 kg object has no or 0 potential energy, as one can compute the potential energy as Ep = mgh. Since the object is on the ground it posses no height and thus no potential energy.

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Consider an object on a rotating disk a distance r from its center, held in place on the disk by static friction. Which of the f

SVEN [57.7K]

Answer:

A) False

B) False

C) True

D) True

E) True

Explanation:

A) The formula for tangential speed v in term of angular speed ω and radius of rotation r is

$v = \omega r$

So if the angular speed is constant and 0, the tangential speed is also 0. A) is false

B) False because of the centripetal acceleration:

$a_c = \omega^2 r$

C) True because of the formula for tangential acceleration in term of angular acceleration α is

$a_t = \alpha r$

D) True because same as D), if it has angular acceleration, it would have a tangential acceleration. Also from B) the centripetal acceleration will come with time as soon as angular speed is generated by angular acceleration.

E) True and same explanation as from B)

8 0

3 years ago

Suppose that a spiral galaxy is located at the center of a spherically symmetric dark matter halo

Novosadov [1.4K]

To solve the problem it is necessary to use the concepts of Orbital Speed considering its density, and its angular displacement.

In general terms the Orbital speed is described as,

$V_{orbit} = \sqrt{\frac{G\rho 4\pi r^3}{3}}$

PART A) If the orbital speed of a star in this galaxy is constant at any radius, then,

$\frac{4\pi G\rho r}{3} = \frac{v^2}{r}$

$\frac{4\pi G\rho r}{1} = \frac{3v^2}{r}$

$\frac{\rho}{1} = \frac{3v^2}{r^2 4\pi G}$

$\rho = \frac{1}{r^2}$

PART B) This time we have $v=\omega t$ , where $\omega$ is the angular velocity (constant at this case)

$\frac{4\pi G\rho r}{3} = \frac{v^2}{r}$

$\frac{4\pi G\rho r}{3} = \frac{(\omega r)^2}{r}$

$\rho = \frac{3\omega r}{4\pi Gr}$

$\rho = \frac{3\omega^2}{4\pi G} \propto constant$

PART C) If the total mass interior to any radius r is a constant,

$\frac{4\pi G\rho r}{3} = \frac{v^2}{r}$

$\frac{GM}{r^2}=\frac{v^2}{r}$

$v = \sqrt{\frac{GM}{r}}$

$v= \sqrt{\frac{1}{r}}$

3 0

4 years ago

If the period of the lowest-frequency sound you can hear is 0.050 s, then what is its frequency?

seropon [69]

The frequency of a sound wave or any wave for that matter is the reciprocal of the period. That is,
f = 1/T
Substituting the known value of period,
f = 1/(0.05 s)
f = 20 Hz
Thus, the frequency of the wave is equal to 20 Hz.

8 0

4 years ago

What is the magnitude of the largest net force that can be produced by combining a force of 6.0 N

ololo11 [35]

Answer:

10N

Explanation:

The formula for calculating the resultant is expressed as;

R = √F1²+F2²

F1 and F2 are the forces

Given

F1 = 6.0N

F2 = 8.0N

R = √6²+8²

R = √36+64

R = √100

R = 10.0N

Hence the magnitude of the net force is 10N

4 0

3 years ago

Mass refers to the gravitational force on the matter in contact with the surface of a planet

Arte-miy333 [17]

Answer: Yes and no.

Explanation: Mass is the amount of matter in an object, whereas weight is the force exerted on an object by gravity. Objects on the surface of the earth have weight, although sometimes the weight is difficult to measure.

8 0

4 years ago