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vichka [17]
3 years ago
7

A car engine burns gas at 495 K, and exhausts to the air at 293 K. If it ran at the highest possible efficiency, how much input

heat would it take to do 10,000 J of work? (Unit=J)
Physics
1 answer:
slamgirl [31]3 years ago
4 0

  The heat taken to do the 10,000 J of work is 4081 J

<u>Explanation:</u>

The ratio of the temperature difference between the reservoirs and the temperature of the hot reservoir is termed as maximum thermal efficiency.

Maximum thermal efficiency is

                                                   1 - (Tc / Th).

where Tc represents the  absolute temperature of the cold reservoir

           Th represents the absolute temperature of the hot reservoir.

                                                    1 - (293/495) = 0.408  

If the input is 10,000 J, then 4081 J is used to do work.  The remaining 5919 J is rejected as heat into the air.

You might be interested in
10. A boat traveling at 9.5 m/s reduces its acceleration at a rate of 2.5 m/s2. What is the final speed of the boat
Fiesta28 [93]

Answer:

6.75m/s

Explanation:

using the second equation of motion, the time is calculated.

and with the formula a= (v - u)/t

where a is acceleration but in this case it's deceleration (and should be negated as you solve it ) .

v is final velocity

u is initial velocity

t is time taken

7 0
2 years ago
An ideal spring is fixed at one end. A variable force F pulls on the spring. When the magnitude of F reaches a value of 43.8 N,
maw [93]

A force of 43.8 N is required to stretch the spring a distance of 15.5 cm = 0.155 m, so the spring constant <em>k</em> is

43.8 N = <em>k</em> (0.155 m)   ==>   <em>k</em> = (43.8 N) / (0.155 m) ≈ 283 N/m

The total work done on the spring to stretch it to 15.5 cm from equilibrium is

1/2 (283 N/m) (0.155 m)² ≈ 3.39 J

The total work needed to stretch the spring to 15.5 cm + 10.4 cm = 25.9 cm = 0.259 m from equilibrium would be

1/2 (283 N/m) (0.259 m)² ≈ 9.48 J

Then the additional work needed to stretch the spring 10.4 cm further is the difference, about 6.08 J.

5 0
3 years ago
A +71 nC charge is positioned 1.9 m from a +42 nC charge. What is the magnitude of the electric field at the midpoint of these c
viva [34]

Answer:

The net Electric field at the mid point is 289.19 N/C

Given:

Q = + 71 nC = 71\times 10^{- 9} C

Q' = + 42 nC = 42\times 10^{- 9} C

Separation distance, d = 1.9 m

Solution:

To find the magnitude of electric field at the mid point,

Electric field at the mid-point due to charge Q is given by:

\vec{E} = \frac{Q}{4\pi\epsilon_{o}(\frac{d}{2})^{2}}

\vec{E} = \frac{71\times 10^{- 9}}{4\pi\8.85\times 10^{- 12}(\frac{1.9}{2})^{2}}

\vec{E} = 708.03 N/C

Now,

Electric field at the mid-point due to charge Q' is given by:

\vec{E'} = \frac{Q'}{4\pi\epsilon_{o}(\frac{d}{2})^{2}}

\vec{E'} = \frac{42\times 10^{- 9}}{4\pi\8.85\times 10^{- 12}(\frac{1.9}{2})^{2}}

\vec{E'} = 418.84 N/C

Now,

The net Electric field is given by:

\vec{E_{net}} = \vec{E} - \vec{E'}

\vec{E_{net}} = 708.03 - 418.84 = 289.19 N/C

5 0
3 years ago
WILL GIVE BRAINLIEST PLZ HELP REALLY URGENT
ozzi
D.) 5kg

This is a trick question. The mass of an object does not change based in location. However the weight of an object does change, this is because Weight = Mass × Gravity. Also mass is measured in kilograms and so the answer is 5 kg. So if you ever want to lose weight just go to the moon!
3 0
3 years ago
A dragster travels 1/4 mi in 6.7 s. Assuming that acceleration is constant and the dragster is initially at rest, what is its ve
nlexa [21]
V0=0m/s (initially at rest)
t=6,7s
s=1/4mi=402,336m
s=(a*t^2)/2   ->   a=2*s/t^2    ->  a=2*402,336m/(6,7s)^2
a=804,672/44,89=17,93 m/s^2
<span>v=v0+at
</span>v=0+17,93 m/s^2 * 6,7s = 120,131 m/s = 432,4716 km/h
3 0
3 years ago
Read 2 more answers
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