A 5,400 W motor is used to do work. If the motor is used for 640 s, about how much work could it do?

Which of the following is the best thermal insulator?

serious [3.7K]

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.

3 0

3 years ago

Read 2 more answers

The weighted average of the masses of the isotopes of an element

solmaris [256]

Answer:

Atomic mass

Explanation:

The weighted average of the masses of the various isotopes of an element makes the atomic mass. This is why most atomic mass values usually have decimals.

In order to calculate the atomic mass of an element using the weighted average masses, we use the expression below:

Atomic mass = ∑ $m_{i}$ $α_{i}$

Where $m_{i}$ is the mass of isotope i

$α_{i}$ is the abundance of isotope i

The abundance or geonormal abundance is the proportion by which each of the isotope occurs in nature.

4 0

3 years ago

A bus accelerates to 60 m/s to the east in 10 s. What is the buses acceleration? 2. A car traveling at 10.0 m/s to the west acce

professor190 [17]

Answers:

1) $a=6\frac{m}{s^{2}}$

2) $t=8s$

Explanation:

1) Acceleration $a$ is defined as the variation of Velocity $V$ in time $t$ :

$a=\frac{V}{t}$ (1)

A body also has acceleration when it changes its direction.

In this case we have a bus with a velocity of 60m/s to the east, that accelerates in a time 10s. So, we have to find the bus's acceleration:

$a=\frac{60m/s}{10s}$ (2)

$a=6m/s^{2}$ (3) This is the bus's accelerration

2) Now we have a car that accelerates $2m/s^{2}$ to the west in order to reach a speed of $16m/s$ in the same direction, and we have to find the time $t$ it takes to the car to reach that velocity.

Therefore we have to find $t$ from (1):

$t=\frac{V}{a}$ (4)

$t=\frac{16m/s}{2m/s^{2}}$ (5)

Finally:

$t=8s$ (6)

3 0

4 years ago

How to read a micrometer on a clark cm-100 vickers hardness tester

allsm [11]

Answer:

Explanation:

Equipment manufactured by LECO(8 Corporation, St. Joseph, Michigan is warranted free from defect in material

and workmanship for a period of six months from the date of purchase. Equipment not manufactured by LECO is

covered to the extent of warranty provided by the original manufacturer and this warranty does not cover any

equipment, new or used, purchased from anyone other than the LECO Corporation. All replacement parts shall

be covered under warranty for a period of thirt days from date of purchase. LECO MAKES NO OTHER

REPRESENTATION OR WARRANTY OF ANY OTHER KIND, EXPRESSED OR IMPLIED, WITH RESPECT TO

THE GOODS SOLD HEREUNDER, WHETHER AS TO MERCHANTABILITY, FITNESS FOR PURPOSE, OR

OTHERWISE.

Expendable items such as crucibles, combustion tubes, chemicals and items of like nature are not covered by

this warranty.

LECO's sole obligation under this warranty shall be to repair or replace any part or parts which, to our

satisfaction, prove to be defective upon return prepaid to LECO Corporation, St. Joseph, Michigan. This

obligation does not include labor to install replacement parts, nor does it cover any failure due to accident, abuse,

neglect, or use in disregard of instructions furnished by LECO. In no event shall damages for defective goods

exceed the purchase price of the goods, and LECO SHALL NOT BE LIABLE FOR INCIDENTAL OR

CONSEQUENTIAL DAMAGES WHATSOEVER.

All claims in regard to the parts or equipment must be made within ten (10) days after Purchaser learns of the

facts upon which the claim is based. Authorization must be obtained from LECO prior to returning any other

parts. This warranty is voided by failure to comply with these notice requirements.

NOTICE

The warranty on LECO equipment remains valid only when genuine LECO replacernent parts are employed.

Since LECO has no control over the quality or purity of consumable products not manufactured by LECO, the

specifications for accuracy of results using LECO instruments are not guaranteed unless genuine LECO

consumables are employed in conjunction with LECO instruments. If purchaser defaults in making payment for

any parts or equipment, this warranty shall be void and shall not apply to such parts and equipment. No late

payment or cure of default in payment shall extend the warranty period provided herein.

LECO Corporation is not responsible for damage to any associated instruments, equipment or apparatus nor wil

LECO be held liable for loss of profit or other special damages resulting from abuse, neglect, or use in disregard

of instructions. The Buyer, their employees, agents and successors in interest assume all risks and liabilities for

the operation, use and/or misuse of the product(s) described herein and agree to indemnify, hold harmless and

defend the seller from any and all claims and actions arising from any cause whatsoever, including seller's

negligence for personal injury incurred in connection with the use of said product(s) and any and all damages

proximately resulting therefrom.

CAUTION

The instrument should be operated only by technically qualified individuals who have fully read and understand

these instructions. The instrument should be operated only in accordance with these instructions.

The operator should follow all ,of the warnings and cautions set forth in the manual and the operator should follow

and employ all applicable standard laboratory safety procedures.

LECO'" is a registered trademark of the LECO Corporatio

5 0

2 years ago

You drive a car 1600 ft to the east, then 2500 ft to the north. The trip took 2.5 minutes. What was the magnitude of your averag

elena-14-01-66 [18.8K]

Answer:

$Velocity=6.03m/s$

Explanation:

Given data

Time t=2.5 minutes=150 seconds

Distance A=1600 ft=487.68 m........east

Distance B=2500 ft=762m ........north

To find

Average velocity

Solution

First we need to find the resultant distance magnitude.To find that we apply Pythagorean theorem to find hypotenuse

So

$A^{2}+B^{2}=C^{2}\\ C=\sqrt{A^{2}+B^{2}}\\ C=\sqrt{(487.68m)^{2}+(762m)^{2}}\\ C=904.7m$

$Velocity=\frac{Distance}{Time}\\Velocity=\frac{904.7m}{150s}\\Velocity=6.03m/s$

7 0

3 years ago