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3 years ago

A compact disc has a radius of 6 centimeters.

2 answers:

5 0

Circumference is $2\pi{r}=37.7$ (approx.)
Speed is 4 times that. That is, 150.8 cm/s or 1.508 m/s.
If we get a point at distance 3 cm, we take the radius half of that. The circumference also gets half, so does the linear speed. We get 0.754 m/s or 75.398 cm/s.

alex41 [277]3 years ago

5 0

Answer:75.389

Explanation:

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Michael Jordan, el célebre basquetbolista, ganó el torneo de clavadas de la NBA en 1988. Para lograr la hazaña saltó 1.35 metros

kozerog [31]

(a) 0.40 s

First of all, let's find the initial speed at which Jordan jumps from the ground.

The maximum height is h = 1.35 m. We can use the following equation:

$v^2-u^2=2gh$

where

v = 0 is the velocity at the maximum height

u is the initial velocity

$g=-9.8 m/s^2$ is the acceleration of gravity

Solving for u,

$u=\sqrt{-2gh}=\sqrt{-2(-9.8)(1.35)}=5.14 m/s$

The time needed to reach the maximum height can now be found by using the equation

$v=u+gt$

Solving for t,

$t=\frac{v-u}{g}=\frac{0-5.14}{-9.8}=0.52s$

Now we can find the velocity at which Jordan reaches a point 20 cm below the maximum height, so at a height of

h' = 1.35 - 0.20 = 1.15 m

Using again the equation

$v'^2-u^2=2gh'$

we find

$v'=\sqrt{u^2+2gh}=\sqrt{5.14^2+2(-9.8)(1.15)}=1.97 m/s$

And the corresponding time is

$t'=\frac{v'-u}{g}=\frac{1.97-5.14}{-9.8}=0.32s$

So the time to go from h' to h is

$\Delta t = t-t'=0.52-0.32=0.20 s$

And since we have also to take into account the fall down (after Jordan reached the maximum height), which is symmetrical, we have to multiply this time by 2 to get the total time of permanence in the highest 20 cm of motion:

$\Delta t=2\cdot 0.20 = 0.40 s$

(b) 0.08 s

This part is easier since we need to calculate only the velocity at a height of h' = 0.20 m:

$v'^2-u^2=2gh'$

$v'=\sqrt{u^2+2gh}=\sqrt{5.14^2+2(-9.8)(0.20)}=4.74 m/s$

And the corresponding time is

$t'=\frac{v'-u}{g}=\frac{4.74-5.14}{-9.8}=0.04s$

So this is the time needed to go from h=0 to h=20 cm; again, we have to take into account the motion downwards, so we have to multiply this by 2:

$\Delta t = 2\cdot 0.04 =0.08 s$

8 0

3 years ago

A charge of 7.2 × 10-5 C is placed in an electric field with a strength of 4.8 × 105 StartFraction N over C EndFraction. If the

barxatty [35]

Answer:

2.2 meters

Explanation:

Potential energy, PE created by a charge, q at a radius r from the charge source, Q, is expressed as:

$KE=\frac{kQq}{r}\ \ \ \ \ \ \ ...i$

$k$ is Coulomb's constant.

#The electric field, $E$ at radius r is expressed as:

$E=\frac{kQ}{r^2}\ \ \ \ \ \ \ \ \ \ ...ii$

From i and ii, we have:

$KE=Eqr$

$r=(KE)/Eq$

#Substitute actual values in our equation:

$r=\frac{75J}{(7.2\times 10^{-5}C)(4.8\times 10^5 V/m)}\\\\=2.1701\approx2.2\ m$

Hence, the distance between the charge and the source of the electric field is 2.2 meters

7 0

3 years ago

Read 2 more answers

Which is the best description of inertia? Inertia is

valentinak56 [21]

Answer:

The best description of inertia is an objects velocity

8 0

3 years ago

Can you describe Saturn?

Arte-miy333 [17]

<span>Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius about nine times that of Earth.</span>

6 0

3 years ago

A skateboarder with a mass of 67.0 kilograms (including the skateboard) rolls down from the top of a ramp, reaching a velocity o

Llana [10]

The potential energy of the skateboarder at the top of the ramp is

489.1 J.

<h3>Is kinetic energy always equal to potential energy?</h3>

The amount of kinetic energy change and the amount of potential energy change are equal in all physical processes that take place in closed systems. When the kinetic energy rises, the potential energy falls, and vice versa.

Potential energy is the stored energy in any object or system as a result of its position or component arrangement. However, external factors like air or height have no effect on it. The energy of a moving object or system is referred to as kinetic energy.

Potential energy = kinetic energy

Potential energy = 1/2mv²

Potential energy = 1/2 × 67×7.3

Potential energy = 489.1 J.

To know more about kinetic energy visit:

brainly.com/question/26472013

#SPJ1

5 0

1 year ago