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valentinak56 [21]

2 years ago

11

A heat engine has a thermal efficiency of 45%. how much power does the engine produce when heat is transferred into it at a rate

of 109 kj/hr?

1 answer:

Masja [62]2 years ago

8 0

It will put out 49.05 kj/hr Multiply efficiency by the rate at which heat is being transfered. 45%=.45
109*.45=49.05

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A balloon is at a height of 81m and is ascending upwards with a velocity of 12m/s. A body of 2kg weight is dropped from it. If g

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Sladkaya [172]

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2 years ago

Four students measured the acceleration of gravity. The accepted value for their location is 9.78m/s2. Which student’s measureme

Lisa [10]

On comparing values , we see that student which has the largest percent error is <u>A. Student 4: 9.61 m/s2 .</u>

<u>Explanation:</u>

Here, we have Four students measured the acceleration of gravity. The accepted value for their location is 9.78m/s2. Let's calculate which student’s measurement has the largest percent error :

<u>A. Student 4: 9.61 m/s2 </u>

Percentage of error = $\frac{9.78-9.61}{9.78} (100) = 1.738%$ %.

<u>B. Student 3: 9.88 m/s2 </u>

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<u>C. Student 2: 9.79 m/s2 </u>

Percentage of error = $\frac{9.79-9.78}{9.78} (100) = 0.1022%$ % .

<u>D. Student 1: 9.78 m/s2</u>

Percentage of error = $\frac{9.78-9.61}{9.78} (100) = 0%$ % .

On comparing values , we see that student which has the largest percent error is <u>A. Student 4: 9.61 m/s2 .</u>

4 0

2 years ago

irina [24]

Answer:

v' = -18 m/s

Explanation:

Assuming no external forces acting during the collision, total momentum must be conserved, as follows:

$p_{o} = p_{f} (1)$

The initial momentum can be expressed as follows (taking as positive the initial direction of the ball):

$m_{b} * v_{b} -M_{c}*V_{c} = m_{b} * 18 m/s + (-M_{c}* 20 m/s) (2)$

The final momentum can be expressed as follows (since we know that v'b is opposite to the initial vb):

$-(m_{b} * v'_{b}) + M_{c}*V'_{c} (3)$

If we assume that Mc >> mb, we can assume that the car doesn't change its speed at all as a result of the collision, so we can replace V'c by Vc in (3).
So, we can write again (3) as follows:

$-(m_{b} * v'_{b}) +(- M_{c}*V_{c}) = -(m_{b} * v'_{b}) + (-M_{c} * 20 m/s) (4)$

Replacing (2) and (4) in (1), we get:

$m_{b} * 18 m/s + (-M_{c}* 20 m/s) = -(m_{b} * v'_{b}) + (-M_{c} * 20 m/s) (5)$

Simplifying, and rearranging, we can solve for v'b, as follows:
$v'_{b} = -18 m/s (6)$ , which is reasonable, because everything happens as if the ball had hit a wall, and the ball simply had inverted its speed after the collision.

3 0

1 year ago

A 52 N sled is pulled across a cement sidewalk at constant speed. A horizontal force of 36 N is exerted. What is the coefficient

Andre45 [30]

Answer:

μ = 0.692

Explanation:

In order to solve this problem, we must make a free body diagram and include the respective forces acting on the body. Similarly, deduce the respective equations according to the conditions of the problem and the directions of the forces.

Attached is an image with the respective forces:

A summation of forces on the Y-axis is performed equal to zero, in order to determine the normal force N. this summation is equal to zero since there is no movement on the Y-axis.

Since the body moves at a constant speed, there is no acceleration so the sum of forces on the X-axis must be equal to zero.

The frictional force is defined as the product of the coefficient of friction by the normal force. In this way, we can calculate the coefficient of friction.

The process of solving this problem can be seen in the attached image.

5 0

2 years ago