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Evgen [1.6K]
3 years ago
13

A motorcyclist drives from a to b with the uniform speed of 30 km/h-1 and returns back with the speed of 20 km/h-1.find the aver

age speed?
Physics
2 answers:
Contact [7]3 years ago
5 0
Average speed= total distance/total time  

FIRST JOURNEY

A..................s=30km/hr..............d=x......................B

RETURN JOURNEY

B...................s=20km/hr..............d=x......................A

Total Distance=2x

Total Time= x/30km/hr + x/20km/hr = 5x/60

AVS=TD/TT      2x/5x/60   2x divide 5x/60 ANSWER is 24km/hr
maxonik [38]3 years ago
4 0
30+20 =50
For average 50/2=25
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Some machines do not multiply the force that is applied to them
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Answer:

Machine Efficiency

Explanation:

Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work). The output work is always less than the input work because some of the input work is used to overcome friction. Therefore, efficiency is always less than 100 percent

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You need to build a prototype with machined parts that withstand a saline corrosive environment and temperatures above 200 degre
kondor19780726 [428]

Answer:

Stainless steel

Explanation:

I will try to order the solutions from the least correct to the most correct.

Since a temperature greater than 200 ° F is required, that is to say approximately 93 ° c, <em>Polycaprolactone</em> is the least indicated. Its melting point is approximately 60 ° C, so it would not serve the required application.

On the other hand we have<em> Untreated aluminum</em>, which although it has a melting point higher than the required one, without a zinc and magnesium treatment it will easily oxidize in a salty environment, so it cannot be used in this choice either.

We have to compare the two steels.

The<em> Mild Steel </em>has a better corrosion resistance than the previous ones, but in a long-term cycle it will end up full of corrosion and therefore its properties will be highly affected.

Finally, we have <em>stainless steel</em>, which, as the name implies, contains in some of its variations chromium, zinc or magnesium in its alloys, which makes it highly resistant to corrosion.

In addition its melting point is above 1500 ° c.

The best choice is stainless steel.

5 0
3 years ago
An automobile traveling on a straight, level road has an initial speed v when the brakes are applied. In coming to rest with a c
Molodets [167]

Answer:

4x

Explanation:

Use v^{2} = u^{2} +2as to do the question.

For first instance,

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for second instance,

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So by (1) and (2),

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3 0
3 years ago
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ki77a [65]

Answer:

Option (d) is correct.

Explanation:

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The SI unit of force is Newton (N) and that of displacement is meter (m). So, the unit of work done is N-m. It is call Joule. It means that the unit of work done is Joule.

Power is given by rate at which the work is done. It is given by :

P = W/t, W is work done and t is time

Unit of power:

Unit of work is Joule (J) and that of time is second (s). It means that the unit of power is Watt and it is equal to Joule/second

Hence, the correct option is (d) "The unit for work is a joule. The unit for power is a watt, which is a joule per second".

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