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sertanlavr [38]

3 years ago

14

While a gymnast is in the air during a leap, which of the following quantities must remain constant for her?A) Angular momentum

about her center of massB) positionC) velocityD) momentumE) angular velocity

1 answer:

Alinara [238K]3 years ago

7 0

While a gymnast is in the air during a leap, her Angular momentum about her center of mass<em> (A)</em> and her linear momentum<em> (D)</em> must remain constant for her.

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What happen when a star dies?

Vera_Pavlovna [14]

It depends on the size of the star. If it's size was normal then it cools down into White dwarf, then a black dwarf. If a really huge star dies, then we can see a "Supernova" from that.

Hope this helps!!

7 0

3 years ago

the 200 g baseball has a horizontal velocity of 30 m/s when it is struck by the bat, B, weighing 900 g, moving at 47 m/s. during

Ivanshal [37]

Solution :

Given :

Mass of the baseball, m = 200 g

Velocity of the baseball, u = -30 m/s

Mass of the baseball after struck by the bat, M = 900 g

Velocity of the baseball after struck by the bat, v = 47 m/s

According to the conservation of momentum,

$Mv+mu=Mv_1+mv_2$

(900 x 47) + (200 x -30) = (900 x $v_1$ ) + (200 x $v_2$ )

36300 = (900 x $v_1$ ) + (200 x $v_2$ )

$9v_1 + 2v_2 = 363$ ..............(i)

$9v_1 = 363 - 2v_2$

$v_1=\frac{363 - 2v_2}{9}$

The mathematical expression for the conservation of kinetic energy is

$\frac{1}{2}Mv^2+\frac{1}{2}mu^2 = \frac{1}{2}Mv_1^2+\frac{1}{2}mv_2^2$

$\frac{1}{2}(900)(47)^2+\frac{1}{2}(200)(-30)^2 = \frac{1}{2}(900)v_1^2+\frac{1}{2}(200)v_2^2$ ................(ii)

$(9)(14)^2+(2)(-30)^2 = (9)v_1^2+2v_2^2$

$21681 = 9v_1^2+2v_2^2$

Substituting (i) in (ii)

$21681= 9\left( \frac{363-2v_2}{9}\right)^2+2v_2^2$

$(363-2v_2)^2+18v_2^2=195129$

$(363)^2+18v_2^2-2(363)(2v_2)+(363)^2-195129=0$

$22v_2^2-145v_2-63360=0$

Solving the equation, we get

$v_2=96 \ m/s, -30 \ m/s$

The negative velocity is neglected.

Therefore, substituting 96 m/s for $v_2$ in (i), we get

$v_1=\frac{363-(2 \times 96)}{9}$

= 19

Thus, only impulse of importance is used to find final velocity.

8 0

3 years ago

A robot is exploring charon, the dwarf planet pluto's largest moon. Gravity on charon is 0.278 meters per second [m divided b

DochEvi [55]

In order to find the efficiency first we will find the Change in Potential energy of the small stone that robot picked up

First we will find the mass of the stone

As it is given that stone is spherical in shape so first we will find its volume

$V = \frac{4}{3}\pi r^3$

$V = \frac{4}{3}\pi *(\frac{0.06}{2})^3$

$V = 1.13 * 10^{-4} m^3$

Now it is given that it's specific gravity is 10.8

So density of rock is

$\rho = 10.8 * 10^3 kg/m^3$

mass of the stone will be

$m = \rho V$

$m = 10.8* 10^3 * 1.13 * 10^{-4}$

$m = 1.22 kg$

now change in potential energy is given as

$\Delta U = mgH$

here

g = gravity on planet = 0.278 m/s^2

H = height lifted upwards = 15 cm

$\Delta U = 1.22* 0.278 * 0.15$

$\Delta U = 0.051 J$

Now energy supplied by internal circuit of robot is given by

$E = Vit$

V = voltage supplied = 10 V

i = current = 1.83 mA

t = time = 12 s

$E = 10* 1.83 * 10^{-3} * 12$

$E = 0.22 J$

Now efficiency is defined as the ratio of output work with given amount of energy used

$\eta = \frac{\Delta U}{E}*100$

$\eta = \frac{0.051}{0.22} = 0.23$

so efficiency will be 23 %

5 0

3 years ago

A resistor, an inductor, and a switch are all connected in series to an ideal battery of constant terminal voltage. Suppose at f

Airida [17]

Answer:

c. The steady-state value of the current depends on the resistance of the resistor.

Explanation:

Since all the components are connected in series, when the switch is at first open, current will not flow round the circuit. As current needs to flow through from the positive terminal of the battery through the resistor, inductor, and switch to the negative terminal of the battery.

But the moment the switch is closed, at the initial time t = 0, the current flow through from the positive terminal of the battery through the resistor, inductor, and switch to the negative terminal of the battery. It then begins to increase at a rate that depends upon the value of the inductance of the inductor.

6 0

3 years ago

which observation about the Mid-Atlantic Ridge region provides the best evidence of the seafloor has been spreading over for mil

Kitty [74]

Magnetic stripes on the sea floor

Explanation:

The observation of magnetic stripes patterns at the region of the Mid-Atlantic Ridge galvanized the evidence that sea floor spreading has been on for several millions of years.

Geomagnetic field of the earth is similar to that of bar magnet having the north and south pole.
It originates from the movement of iron-nickel within the outer core.
This geomagnetic field causes the magnetization of magnetic minerals in rock.
When freshly formed magma is brought to the surface at the mid oceanic ridge area, the prevailing magnetic field causes the magnetic minerals in the magma to cool in such a way that they align their domains to that of the field.
The magnetic field of the earth can reverse and take different geometry. Sometimes, its intensity is very strong and at other times it is weak.
The magnetic minerals in melts bear these records.
As new materials are brought up, they get magnetized.

Learn more:

Sea floor spreading brainly.com/question/9912731

#learnwithBrainly

8 0

3 years ago