The amount of matter in an object

A uniform disk has a mass of 3.7 kg and a radius of 0.40 m. The disk is mounted on frictionless bearings and is used as a turnta

nevsk [136]

Answer:

1.25 kgm²/sec

Explanation:

Disk inertia, Jd =

Jd = 1/2 * 3.7 * 0.40² = 0.2960 kgm²

Disk angular speed =

ωd = 0.1047 * 30 = 3.1416 rad/sec

Hollow cylinder inertia =

Jc = 3.7 * 0.40² = 0.592 kgm²

Initial Kinetic Energy of the disk

Ekd = 1/2 * Jd * ωd²

Ekd = 0.148 * 9.87

Ekd = 1.4607 joule

Ekd = (Jc + 1/2*Jd) * ω²

Final angular speed =

ω² = Ekd/(Jc+1/2*Jd)

ω² = 1.4607/(0.592+0.148)

ω² = 1.4607/0.74

ω² = 1.974

ω = √1.974

ω = 1.405 rad/sec

Final angular momentum =

L = (Jd+Jc) * ω

L = 0.888 * 1.405

L = 1.25 kgm²/sec

4 0

4 years ago

Climate Change has been a hot topic in the news, politics, and science. To help clarify the issue, address the following:

yuradex [85]

I can answer number 2 for you only. I don’t know if it’s correct or not this is what I THINK it is:

2. Burning fossil fuels creates greenhouse gases, which changes the climate.
Ps. Climate is long term weather. Aka weather over a long period of time.

3 0

3 years ago

4. Compare the change in initial and final gravitational force in

mylen [45]

Gravitational force equals GMm/r^2, where G is constant, M and m are the masses, and r is distance.

For I, if both masses double, the formula becomes G2M2m/r^2, or 4GMm/r^2. Therefore, the gravitational force will quadruple or 4x.

For II, if the distance between the object doubles, the formula becomes GMm/(2r)^2 or GMm/4r^2. In this case, the gravitational force is 1/4x the initial force.

4 0

3 years ago

A sanding disk with rotational inertia 3.8 x 10-3 kg·m2 is attached to an electric drill whose motor delivers a torque of magnit

Elis [28]

Answer:

(a) Angular momentum of disk is $1.343\, \frac{kg.m^{2}}{s}$

(b) Angular velocity of the disk is $353\frac{rad}{s}$

Explanation:

Given

Rotational inertia of the disk , $I=3.8\times 10^{-3}kg.m^{2}$

Torque delivered by the motor , $\tau =17N.m$

Torque is applied for duration , $\Delta t=79ms=0.079s$

(a)

Magnitude of angular momentum of the disk = Angular impulse produced by the torque

$\therefore L=\tau \Delta t=17\times 0.079\frac{kg.m^{2}}{s}$

=> $L=1.343\, \frac{kg.m^{2}}{s}$

Thus angular momentum of disk is $1.343\, \frac{kg.m^{2}}{s}$

(b)

Since Angular momentum , $L=I\omega$

where $\omega$ = Angular velocity of the disk

$=>\omega =\frac{L}{I}=\frac{1.343}{3.8\times 10^{-3}}\frac{rad}{s}$

$\therefore \omega =353\frac{rad}{s}$

Thus angular velocity of the disk is $353\frac{rad}{s}$

5 0

3 years ago

Compute the order of magnitude of the mass of a bathtub half full of pennies. (Assume the pennies are made entirely of copper.)

devlian [24]

Answer:

Mass = 873.6kg = 0.874 × 10^3 kg

Order = 3

Question:

Compute the order of magnitude of the mass of a bathtub half full of pennies.(Assume the pennies are made entirely of copper and the tub measures 1.3 m by 0.5 m by 0.3 m)

Explanation:

Given:

Dimensions of the tub = 1.3 m by 0.5 m by 0.3 m

Density of copper d = 8960kg/m^3

Mass = volume × density

Volume of tub = L×B×H = 1.3 × 0.5 × 0.3 = 0.195m^3

Since the tub is half full:

V = 0.195/2 = 0.0975m^3

Mass = 8960kg/m^3 × 0.0975m^3

Mass = 873.6kg = 0.874 × 10^3 kg

Order = 3

Note: Order of magnitude is of the form:

N = a × 10^b

Where;

b = order of magnitude

and

1/√10 </= a < √10

8 0

4 years ago