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ahrayia [7]
3 years ago
11

Which of the device has the highest resistance?

Physics
2 answers:
-BARSIC- [3]3 years ago
5 0
It would be c) Rheostat
Margarita [4]3 years ago
5 0
I think it would be c
You might be interested in
A 54 kg person stands on a uniform 20 kg, 4.1 m long ladder resting against a frictionless wall.
SVETLANKA909090 [29]

A) Force of the wall on the ladder: 186.3 N

B) Normal force of the ground on the ladder: 725.2 N

C) Minimum value of the coefficient of friction: 0.257

D) Minimum absolute value of the coefficient of friction: 0.332

Explanation:

a)

The free-body diagram of the problem is in attachment (please rotate the picture 90 degrees clockwise). We have the following forces:

W=mg: weight of the ladder, with m = 20 kg (mass) and g=9.8 m/s^2 (acceleration of gravity)

W_M=Mg: weight of the person, with M = 54 kg (mass)

N_1: normal reaction exerted by the wall on the ladder

N_2: normal reaction exerted by the floor on the ladder

F_f = \mu N_2: force of friction between the floor and the ladder, with \mu (coefficient of friction)

Also we have:

L = 4.1 m (length of the ladder)

d = 3.0 m (distance of the man from point A)

Taking the equilibrium of moments about point A:

W\frac{L}{2}sin 21^{\circ}+W_M dsin 21^{\circ} = N_1 Lsin 69^{\circ}

where

Wsin 21^{\circ} is the component of the weight of the ladder perpendicular to the ladder

W_M sin 21^{\circ} is the component of the weight of the man perpendicular to the ladder

N_1 sin 69^{\circ} is the component of the normal  force perpendicular to the ladder

And solving for N_1, we find the force exerted by the wall on the ladder:

N_1 = \frac{W}{2}\frac{sin 21^{\circ}}{sin 69^{\circ}}+W_M \frac{d}{L}\frac{sin 21^{\circ}}{sin 69^{\circ}}=\frac{mg}{2}\frac{sin 21^{\circ}}{sin 69^{\circ}}+Mg\frac{d}{L}\frac{sin 21^{\circ}}{sin 69^{\circ}}=\frac{(20)(9.8)}{2}\frac{sin 21^{\circ}}{sin 69^{\circ}}+(54)(9.8)\frac{3.0}{4.1}\frac{sin 21^{\circ}}{sin 69^{\circ}}=186.3 N

B)

Here we want to find the magnitude of the normal force of the ground on the ladder, therefore the magnitude of N_2.

We can do it by writing the equation of equilibrium of the forces along the vertical direction: in fact, since the ladder is in equilibrium the sum of all the forces acting in the vertical direction must be zero.

Therefore, we have:

\sum F_y = 0\\N_2 - W - W_M =0

And substituting and solving for N2, we find:

N_2 = W+W_M = mg+Mg=(20)(9.8)+(54)(9.8)=725.2 N

C)

Here we have to find the minimum value of the coefficient of friction so that the ladder does not slip.

The ladder does not slip if there is equilibrium in the horizontal direction also: that means, if the sum of the forces acting in the horizontal direction is zero.

Therefore, we can write:

\sum F_x = 0\\F_f - N_1 = 0

And re-writing the equation,

\mu N_2 -N_1 = 0\\\mu = \frac{N_1}{N_2}=\frac{186.3}{725.2}=0.257

So, the minimum value of the coefficient of friction is 0.257.

D)

Here we want to find the minimum coefficient of friction so the ladder does not slip for any location of the person on the ladder.

From part C), we saw that the coefficient of friction can be written as

\mu = \frac{N_1}{N_2}

This ratio is maximum when N1 is maximum. From part A), we see that the expression for N1 was

N_1 = \frac{W}{2}\frac{sin 21^{\circ}}{sin 69^{\circ}}+W_M \frac{d}{L}\frac{sin 21^{\circ}}{sin 69^{\circ}}

We see that this quantity is maximum when d is maximum, so when

d = L

Which corresponds to the case in which the man stands at point B, causing the maximum torque about point A. In this case, the value of N1 is:

N_1 = \frac{W}{2}\frac{sin 21^{\circ}}{sin 69^{\circ}}+W_M \frac{L}{L}\frac{sin 21^{\circ}}{sin 69^{\circ}}=\frac{sin 21^{\circ}}{sin 69^{\circ}}(\frac{W}{2}+W_M)

And substituting, we get

N_1=\frac{sin 21^{\circ}}{sin 69^{\circ}}(\frac{(20)(9.8)}{2}+(54)(9.8))=240.8 N

And therefore, the minimum coefficient of friction in order for the ladder not to slip is

\mu=\frac{N_1}{N_2}=\frac{240.8}{725.2}=0.332

Learn more about torques and equilibrium:

brainly.com/question/5352966

#LearnwithBrainly

7 0
3 years ago
He __________ uses a series of gears to adjust the output speed of the engine.
Verizon [17]
Hey /人 ◕ ‿‿ ◕ 人\
The answer is transmission

uses a series of gears to transmit power to facilitate changes in speed .


GLAD TO HELP


~~~ ╔͎═͓═͙╗
~~~ ╚̨̈́═̈́﴾ ̥̂˖̫˖̥  ̂ )
4 0
3 years ago
Why is thermal energy from the Sun transferred to Earth through electromagnetic waves instead of any other type of thermal energ
liq [111]

Answer:

Because electromagnetic waves can travel through empty space

Explanation:

The energy that is emitted from the sun is transferred to the earth in the form of radioactive waves. These waves are originated due to the vibration between the electric and magnetic fields. As this energy reaches the earth, it warms the earth's atmosphere, resulting in the transfer of heat energy in three possible ways namely the conduction, convection, and radiation.

This electromagnetic waves do not require any matter for the transmission of energy, and can easily travel in empty space from the core of the sun to the earth and other nearby planets. Whereas other types of waves cannot travel in space, so it is transferred in the form of electromagnetic waves only.

8 0
3 years ago
Read 2 more answers
A burglar attempts to drag a 108 kg metal safe across a polished wood floor Assume that the coefficient of static friction is 0.
V125BC [204]

Answer:

2.00 m/s²

Explanation:

Given

The Mass of the metal safe, M = 108kg

Pushing force applied by the burglar,  F = 534 N

Co-efficient of kinetic friction, \mu_k = 0.3

Now,

The force against the kinetic friction is given as:

f = \mu_k N = u_k Mg

Where,

N = Normal reaction

g= acceleration due to the gravity

Substituting the values in the above equation, we get

f = 0.3\times108\times9.8

or

f = 317.52N

Now, the net force on to the metal safe is

F_{Net}= F-f

Substituting the values in the equation we get

 F_{Net}= 534N-317.52N

or

F_{Net}= 216.48

also,

 

F_{Net}= M\timesacceleration of the safe

Therefore, the acceleration of the metal safe will be

acceleration of the safe=\frac{F_{Net}}{M}

or

 acceleration of the safe=\frac{216.48}{108}

or

 

acceleration of the safe=2.00 m/s^2

Hence, the acceleration of the metal safe will be  2.00 m/s²

3 0
2 years ago
sound transfers energy through solid liquid and gas what does ocean waves transfer energy through is it water or water and air a
trapecia [35]
Hears the answer is endocytosis. <span />
7 0
3 years ago
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