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3 years ago

Which of the following is the best thermal insulator?

Physics

2 answers:

Mama L [17]3 years ago

5 0

Answer: A. Air

Explanation: Air is a poor thermal conductor because it's particles are farther apart.

serious [3.7K]3 years ago

3 0

Answer:

A. Air

Explanation:

A thermal insulator is a material that does not let the heat trasmitting through it, or it transmits heat not very efficiently.

Generally, the lower the density of the material, the better insulator the material is: this is because in materials with very low density, particles are very spread apart, so they cannot collide with each other, and so the vibrations of the particles (which determine how hot a substance is) cannot be transmitted very efficiently.

In the options listed in this problem, air is the material with lowest density, therefore it is the best thermal insulator among them.

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In this lab you will use a cart and a track to explore Newton's second law of motion. You will vary two different variables and

Savatey [412]

Answer:

Newtons II law:

It is defined as "the net force acting on the object is a product of mass and acceleration of the body" . Also it defines that the "acceleration of an object is dependent on net force and mass of the body".

Let us assume that,a string is attached to the cart, which passes over a pulley along the track. At another end of the string a weight is attached which hangs over the pulley. The hanging weight provides tension in the spring, and it helps in accelerating the cart. We assume that the string is massless and no friction between pulley and the string.

Whenever the hanging weight moves downwards, the cart will accelerate to right side.

For the hanging weight/mass

When hanging weight of mass is m₁ and accelerate due to gravitational force g.

Therefore we can write F = m₁ .g

and the tension acts in upward direction T (negetive)

Now, Fnet = m₁ .g - T

= m₁.a

So From Newtons II law F = m.a

3 0

3 years ago

Read 2 more answers

A person suffering from hyponatremia has which of the following?a. Too little sodium in the bloodb. Too much sodium in the blood

Art [367]

A person suffering from hyponatremia has too little sodium in the bloodstream. This condition appears when their is more amount of water as compared to solute. it is commonly caused by diarrhea, heart failure and liver disease. Person suffering from this condition must reduce the intake of water.

So the correct choice is

a. Too little sodium in the bloodstream.

6 0

3 years ago

A speeding truck travels in the positive x direction. It hits a car traveling in the positive y direction. The vehicles are defo

marusya05 [52]

Answer:

B. Kinetic energy of the system is partially used up in the deformation of the vehicles.

Explanation:

In an inelastic collision, momentum is conserved, but kinetic energy is not. Kinetic energy is lost as heat or lost in the deformation of the objects.

5 0

3 years ago

Read 2 more answers

In a women's 100-m race, accelerating uniformly, Laura takes 1.82 s and Healan 3.07 s to attain

Sav [38]

Answer:

Laura is ahead and for a distance of 3.22 m

Explanation:

To solve this problem of one-dimensional kinematics, we have to find the acceleration and the final speed of each runner. Let's start with Laura

Lura data is acceleration time 1.82s, total run time 10.4 s and total distance 100m. In all the races the rest starts, so the initial speed is zero (Vo = 0)

Vf1= Vo + a1 t1

Vf1 = x/t

XT = X1 + X2

X1 = Vo t1 + ½ a1 t1²

X1 = ½ a1 t1²

X2 = Vf1 (t-t1)

This is the remaining time of the race after the acceleration is over.

XT = ½ a1 t1² + Vf1 (t-t1)

We remplace the expression of Vf1

XT = ½ a1 t1² + a1 t1 (t-t1)

Laura's aceleration (a1) is

a1= XT / [ ½ t1² + t1 (t-t1)]

a1= 100/ [ ½ 1.82²+ 1.82 (10.4 -1.82)]

a1= 5.79m/s2

We repeat the same calculation for the other Healan runner, whose data are: total distance 100m, acceleration time 3.07 s and total time 10.4 s

Vf2= Vo + a2 t2

Vf2 = x/t

XT = X3 + X4

X3 = Vo t2 + ½ a2 t2²

X3 = ½ a2 t2²

X4 = Vf2 (t-t2)

XT = ½ a2 t2² + Vf2 (t- t2)

XT = ½ a2 t2² + a2 t2 (t-t2)

The aceleration of Healan (a2)

a2 = XT / [½ t2² + t2 (t-t2)]

a2 = 100 / [½ 3,07²+ 3.07 (10.4 -3.07)]

a2 = 3.67 m / s2

We also need the final speeds of each runner

Laura Vf1 = Vo + a1 t1

Vf1 = 0 + 5.79 1.82

Vf1 = 10.54 m / s

Healan Vf2 = Vo + a2 t2

Vf2 = 0 + 3.67 3.07

Vf2 = 11.27 m / s

Having the acceleration and speed of each runner, you can start answering the questions

a) For t3 = 6.15s

Laura

The time to stop with constant speed is what remains after accelerating

XL= ½ a1 t1² + Vf1 (t3-t1)

XL= ½ 5.79 1.82² + 10.54 (6.15 – 1.82)

XL= 55.23 m

Healan

XH= ½ a2 t2² + Vf2 (t3-t2)

XH= ½ 3.67 3.07² + 11.27 (6.15-3.07)

XH= 52.01 m

(XL -XH)= 55.23- 52.01

(XH -XL)= 3.22 m

It is appreciated from these results that Laura is ahead and for a distance of 3.22 m

b) If we analyze the acceleration values of each runner, knowing that they leave the rest and that Healan at the end has a speed greater than Laura, the point of maximum distance difference is when Laura stops accelerating t = 1.82 s

XL= ½ a1 t12

XL= ½ 5.79 1.822

XL= 9.59 m

XH = ½ a2 t12

XH= ½ 3.67 1.822

XH= 6.08 m

The maximum distance difference is 3.51 m

c) Already analyzed in the previous part 1.82 s, since the Laura stop accelerating and Heala continue with acceleration will travel greater distances in equal time units

6 0

3 years ago

The formula v = √ 2.3 r models the maximum safe speed, v , in miles per hour, at which a car can travel on a curved road with ra

Archy [21]

Answer:

562 miles per hour.

Explanation:

As given in the question, the formula for the maximum speed on a curved road is

$v=\sqrt{2.3}$ $r$