^^ help :c

Select the statements that describe a vector. Check all that apply

lozanna [386]

Vectors have both size and direction.
Vectors are indicated with arrows.
Vectors can have positive or negative values.

5 0

3 years ago

A CD has a mass of 17 g and a radius of 6.0 cm. When inserted into a player, the CD starts from rest and accelerates to an angul

Stells [14]

Answer:

τ =9.41 * 10⁻⁴ N*m

Explanation:

Kinematics of the CD

The CD rotates with constant angular acceleration and its angular acceleration is calculated as follows:

$\alpha = \frac{\omega_{f}- \omega_{i}}{t}$ Formula (1)

Where:

α : angular acceleration. (rad/s²)

ωf: final angular velocity (rad/s)

ωi : initial angular velocity (rad/s)

t = time interval (s)

Data

ωf= 20 rad/s

ωi =0

t = 0.65 s.

Calculating of the angular acceleration of the CD

We replace data in the formula (1)

$\alpha = \frac{20 -0}{0.65}$

α = 30.77 rad/s²

Newton's second law in rotation:

F = ma has the equivalent for rotation:

τ = I * α Formula (2)

where:

τ : It is the net torque applied to the body. (N*m)

I : it is the moment of inertia of the body with respect to the axis of rotation (kg*m²)

α : It is angular acceleration. (rad/s²)

Calculating of the moment of inertia of the CD

The moment of inertia of a disk with respect to an axis perpendicular to the plane and passing through its center is calculated by the following formula:

I = (1/2) M*R² Formula (3)

Data

M= 17 g = 17/1000 kg = 0.017 kg : CD mass

R= 6.0 cm= 6/100 m = 0.06 m : CD radius

We replace data in the formula (3) :

I = (1/2) ( 0.017 kg)*(0.06 m)² = 3.06 * 10⁻⁵ kg*m²

Calculating of the net torque acting on the CD

Data

α = 30.77 rad/s²

I = 3.06 * 10⁻⁵ kg*m²

We replace data in the formula (2) :

τ = I * α

τ =( 3.06 * 10⁻⁵ kg*m²) * (30.77 rad/s²)

τ =9.41 * 10⁻⁴ N*m

3 0

3 years ago

Un ladrón viaja en un auto a una velocidad excesiva de 30m/s, en dicho momento un policía de tránsito, lo observa y monta en su

tester [92]

Answer:

t = 12 s

Explanation:

To find the time in which the police reaches the thief you write the equation of motion of both thief and police:

The thief has a constant velocity, the position is then given by:

$x=vt$ (1)

The police has an acceleration, then the position is:

$x=v_ot+\frac{1}{2}at^2$ (2)

the time in which the police reaches the thief is when their positions are equal, that is, when expression (1) equals expression (2). But before you calculate the acceleration of the police:

$a=\frac{v-v_o}{t}\\\\v_o=0m/s\\\\a=\frac{50m/s}{10s}=5\frac{m}{s^2}$

you replace this values in (2) and you equal the expression (1) and (2) (with vo = 0):

$vt=\frac{1}{2}at^2\\\\\frac{1}{2}at^2-vt=0\\\\(\frac{1}{2}at-v)t=0$

one root is t = 0s, but it is omitted because is the momment in which the thief pass in front of the police. The other root is:

$\frac{1}{2}at-v=0\\\\t=\frac{2v}{a}=\frac{(2)(30m/s)}{5m/s^2}=12s$

hence, the time is 12 s

8 0

4 years ago

The kinetic energy of an object depends on two factors, ___, and ___. HINT: Remember comparing the kinetic energy of the marble

Lisa [10]

D. speed | mass
hope this helps

7 0

3 years ago

Read 2 more answers

Radio telescopes beam radio waves into space. To calculate the speed of the radio waves in space, which information, if any, is

Anastaziya [24]

Answer:

No more information is needed

Explanation:

Radio waves are electromagnetic energy, lower frequency forms of this type of energy that includes light and cosmic rays on the high frequency end that we are able to detect. So in free space (vacuum), radio waves travel at their fastest velocity, the “speed of light”. The reason for the quotation marks is because when light or radio waves are propagating through matter, we observe them traveling more slowly.

7 0

3 years ago