Name two careers that use gravity as the main part of the job.

Arte-miy333 [17]

They help keep the country in check because without them there would be chaos

7 0

3 years ago

Consider a thin walled hoop of uniform material. Two axis go through the center of the hoop. One axis is perpendicular to the pl

ratelena [41]

Answer:

Explanation:

Moment of Inertia about an axis passing through its center and Perpendicular to its Plane is given by

$I_{zz}=Mr^2$

As all the mass is at radius therefore its moment of inertia is more than the moment of inertia about a axis parallel to the Plane

According to perpendicular axis theorem

$I_{zz}=I_{xx}+I_{yy}$

and $I_{xx}=I_{yy}$ is same due to symmetry

thus $I_{xx}=\frac{1}{2}\times I_{zz}$

$I_{xx}=\frac{Mr^2}{2}$

thus Perpendicular z axis will have more moment of inertia

7 0

3 years ago

A box sitting still on the ground by itself has a Normal Force of 700N, what is the mass? (gravity’s acceleration is 9.80 m/s²)

Misha Larkins [42]

Answer: 71.43 kilograms

This value is approximate rounded to two decimal places.

=====================================================

Explanation:

The ground is pushing up with a normal force of 700 N. Because the box is sitting still, this means the force of gravity is pulling the box down with a force of 700N to keep things balanced.

If the force of gravity was greater than 700N, then the box would fall through the ground. If the force of gravity was smaller than 700N, then the box would be accelerated upward. Since neither event is happening, the force of gravity must be equal to the normal force.

Now turn to Newton's second law which says

F = ma

where F is the force, m is the mass and 'a' is the acceleration. We're given the acceleration of gravity is roughly 9.80 m/s^2. So a = 9.80

The force we'll plug in is F = 700. The value of m is unknown, but we can solve for it as such

F = ma

700 = m*9.80

700 = 9.08m

9.80m = 700

m = 700/9.80

m = 71.4285714285714

m = 71.43

The mass is roughly 71.43 kilograms.

4 0

3 years ago

You are walking around your neighborhood and you see a child on top of a roof of a building kick a soccer ball. The soccer ball

const2013 [10]

Answer:

The building is 61.19 m tall, approximately.

Explanation:

From the parabollic movement trayectory equation,

$y=H+\frac{v_{0y}}{v_x}x-\frac{1}{2v_x^2}gx^2,$

where H is the initial height of the ball and $v_{oy}$ and $v_x$ the inital velocities in the vertical and horizontal direction, respectively; we have

$H=y-\frac{v_{0y}}{v_x}x+\frac{1}{2v_x^2}gx^2$ .

In this case, the ball landed at the coordinates $\left(x,y\right)=\left(61,0\right)$ , so

$H=0-\frac{17\sin\left(43\deg\right)}{17\cos\left(43\deg\right)}\times 61+\frac{1}{2\left(17\cos\left(43\deg\right)\right)^2}\times 9.81\times 61^2 \approx 61.19$ .

8 0

3 years ago

You are trying to take an image of a particular star with apparent magnitude m=10, and need to figure out how long you will need

Natalka [10]

You haven't told us anything about the detectors being used. We don't know how the sensitivity of the detector is related to the total number of photons absorbed, and we don't even know whether you and your friend are both using the same type of detector.

All we can do, in desperation, is ASSUME that the minimum time required to just detect a star is inversely proportional to the total number of its photons that strike the detector. That is, assume . . .

(double the number of photons) ===> (detect the source in half the time) .

-- The intensity of light delivered to the prime focus of a telescope is directly proportional to the AREA of its objective lens or mirror, which in turn is proportional to the square of its radius or diameter.

So your telescope gathers (0.18/0.05)² = 12.96 times as much light as your friends telescope does.

-- So we'd expect your instrument to detect the same star in

(119.5 min) / (12.96) = <em>9.22 minutes .</em>

We're simply comparing the performance of two different telescopes as they observe the same object, so the star's magnitude doesn't matter.

3 0

3 years ago