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3 years ago

Why are scientific models important ?

Physics

2 answers:

Sindrei [870]3 years ago

7 0

They help scientists explain concepts that are difficult to observe.

ZanzabumX [31]3 years ago

6 0

It depends on the situation but to many they are important because they help visualize things that are very complex.

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The angular momentum of a flywheel having a rotational inertia of 0.142 kg·m2 about its central axis decreases from 7.20 to 0.14

luda_lava [24]

Answer:

3.3619 Nm

54.27472 rad

182.46618 J

86.88 W

Explanation:

$L_i$ = Initial angular momentum = 7.2 kgm²/s

$L_f$ = Final angular momentum = 0.14 kgm²/s

I = Moment of inertia = 0.142 kgm²

t = Time taken

Average torque is given by

$\tau_{av}=\frac{L_f-L_i}{\Delta t}\\\Rightarrow \tau_{av}=\frac{0.14-7.2}{2.1}\\\Rightarrow \tau_{av}=-3.3619\ Nm$

Magnitude of the average torque acting on the flywheel is 3.3619 Nm

Angular speed is given by

$\omega_i=\frac{L_i}{I}$

Angular acceleration is given by

$\alpha=\frac{\tau}{I}$

From the equation of rotational motion

$\theta=\omega_it+\frac{1}{2}\alpha t^2\\\Rightarrow \theta=\frac{L_i}{I}\times t+\frac{1}{2}\times \frac{\tau}{I}\times t^2\\\Rightarrow \theta=\frac{7.2}{0.142}\times 2.1+\frac{1}{2}\times \frac{-3.3619}{0.142}\times 2.1^2\\\Rightarrow \theta=54.27472\ rad$

The angle the flywheel turns is 54.27472 rad

Work done is given by

$W=\tau\theta\\\Rightarrow W=-3.3619\times 54.27472\\\Rightarrow W=-182.46618\ J$

Work done on the wheel is 182.46618 J

Power is given by

$P=\frac{W}{t}\\\Rightarrow P=\frac{-182.46618}{2.1}\\\Rightarrow P=-86.88\ W$

The magnitude of the average power done on the flywheel is 86.88 W

6 0

2 years ago

How much heat is needed to raise the temperature of 2 kg of copper from 20º to 30ºC. The specific heat of copper is 390 J/kgºC.

ryzh [129]

Answer:

7800 J

Explanation:

Heat needed = mass of copper x specific heat of copper x change in temperature

Change in temperature = 30ºC - 20ºC = 10ºC

Specific heat of copper = 390 J/kgºC

Mass of copper = 2 Kg

Substituting the given values in above equation, we get –

Heat needed = 2 Kg x 390 J/kgºC x 10ºC

= 7800 J

3 0

3 years ago

Interactive Solution 9.1 presents a model for solving this problem. The wheel of a car has a radius of 0.380 m. The engine of th

Vilka [71]

Answer:

The magnitude of the static frictional force is 1200 N

Explanation:

given information :

radius, r = 0.380 m

applied-torque, τ1 = 456 N

The car has a constant velocity, thus the acceleration is zero

α = 0

Στ = I α

τ1 - τ2 = I α

τ2 = counter-torque

τ1 - τ2 = 0

τ1 = τ2

r x $F_{s}$ = τ1

$F_{s}$ = the static frictional force (N)

$F_{s}$ = τ1 /r

= 456 N/0.380 m

= 1200 N

7 0

3 years ago

Jill applies a force of 250 N to a machine. The machine applies a force of 25 N to an object. What is the mechanical advantage o

Vinvika [58]

Mechanical advantage is defined as the ratio of output load to the input load. The mechanical advantage of the machine will be 0.1.

<h3>What is mechanical advantage?</h3>

Mechanical advantage is a measure of the ratio of output force to input force in a system,

It is used to obtain the efficiency of forces in levers and pulleys. It is an effective way of amplifying the force in simple machines like levers.

The theoretical mechanical advantage is defined as the ratio of the force responsible for the useful work in the system to the applied force.

Given

applied force = 250 N

Output force = 25

Mechanical advantage = work output / work input

$\rm{Mechanical advantage}=\frac{F_O}{F_I}$

$\rm{Mechanical advantage}=\frac{25}{250}$

$\rm{Mechanical advantage}=0.1$

Hence the mechanical advantage of the machine will be 0.1

To learn more about the mechanical advantage refer to the link;

brainly.com/question/7638820

3 0

2 years ago

A cylinder 0.170 m in diameter rotates in a lathe at 530 rpm . what is the tangential speed of the surface of the cylinder?

Ad libitum [116K]

Diameter = 0.170 meter
Circumference = 0.170 π meters

530 rpm = 530 circumferences / minute

   = (530 x 0.170 π meters) / minute

   =    283.06 meter.minute

   =    4.72 meters/second

8 0

2 years ago