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podryga [215]
4 years ago
12

In one cycle, a heat engine takes in 1000 J of heat from a high-temperature reservoir, releases 600 J of heat to a lower-tempera

ture reservoir, and does 400 J of work. What is its efficiency?
Physics
1 answer:
Talja [164]4 years ago
4 0

Answer:

η = 40 %  

Explanation:

Given that

Qa ,Heat addition= 1000  J

Qr,Heat rejection= 600 J

Work done ,W= 400 J

We know that ,efficiency of a engine given as

\eta=\dfrac{W(net)}{Q(heat\ addition)}

Now by putting the values in the above equation ,then we get

\eta=\dfrac{400}{1000}

η = 0.4

The efficiency in percentage is given as

η = 0.4  x 100 %

η = 40 %

Therefore the answer will be 40%.

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(a)
Lisa [10]

(a) Let the base of the cliff be the origin, so that the rock's height y at time t is

y = h + (8.19 m/s) t - 1/2 gt²

where h is the height of the cliff. The rock hits the ground when y = 0. Solve for h when t = 2.37 s :

0 = h + (8.19 m/s) (2.37 s) - 1/2 (9.80 m/s²) (2.37 s)²

⇒   h ≈ 8.11 m

(b) If the rock is thrown straight down with the same speed, its height at time t would be

y = 8.11 m - (8.19 m/s) t - 1/2 gt²

Solve for t when y = 0 (use the quadratic formula and ignore the negative solution) :

t ≈ 0.699 s

4 0
2 years ago
Help please!!!! Brainlyist to the person who answers
valkas [14]

Answer:

Speed up yes it could depends on initial forces and ending forces

keep in constant motion yes

Slow down yes it could depends on initial forces and ending forces

Change directions yes it could depends on initial forces and ending forces

Could not have a net force of Zero

Explanation:

Speed up yes it could depends on initial forces and ending forces

keep in constant motion yes

Slow down yes it could depends on initial forces and ending forces

Change directions yes it could yes it could depends on initial forces and ending forces

Could not have a net force of Zero

8 0
3 years ago
Read 2 more answers
How do you find the number of negative electrons using the periodic table?
loris [4]

Answer:

By the order its placed in

Explanation:

5 0
3 years ago
What is the measurement 111.009 mm rounded off to four significant digits?
dedylja [7]
111.0 because 111.009 rounds off to 111.01, thus rounding again off to 111.0
4 0
3 years ago
If for every action force an equal and opposite reaction force exists, how can anything ever be accelerated?
Anon25 [30]

The action and reaction forces act on different objects, therefore the net force is not always zero

Explanation:

Newton's third law of motion states that:

<em>"When an object A exerts a force (called action) on an object B, then object B exerts an equal and opposite force (called reaction) on object A"</em>

From the statement above, it is clear that the action and the reaction forces act on different objects. In fact, the action force acts on object B, while the reaction force acts on object A. This means that the two forces never appear in the same free-body diagram of the same object, and therefore when computing the net force acting on an object, we take into account only one of the two forces, never both.

For instance, imagine you are pushing a box along the floor with a force F (action). The box is exerting back on you a reaction force of equal magnitude in the opposite direction, - F. However, if we want to compute the net force on the box, we just take into account the action (F), not the reaction, because the reaction is acting on you, not on the box.

Therefore, the correct answer is

The action and reaction forces act on different objects, therefore the net force is not always zero

Learn more about Newton's third law:

brainly.com/question/11411375

#LearnwithBrainly

3 0
3 years ago
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