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ser-zykov [4K]
2 years ago
12

6–23 an automobile engine consumes fuel at a rate of 22 l/h and delivers 55 kw of power to the wheels. if the fuel has a heating

value of 44,000 kj/kg and a density of 0.8 g/cm3, determine the efficiency of this engine. answer: 25.6 percent
Physics
1 answer:
Anna007 [38]2 years ago
8 0

Explanation & answer:

Given:

Fuel consumption, C = 22 L/h

Specific gravity = 0.8

output power, P  =  55 kW

heating value, H = 44,000 kJ/kg

Solution:

Calculate energy intake

E = C*P*H

= (22 L/h) / (3600 s/h) * (1000 mL/L) * (0.8 g/mL) * (44000 kJ/kg)

= (22/3600)*1000*0.8*44000 j/s

= 215111.1 j/s

Calculate output power

P = 55 kW

= 55000 j/s

Efficiency

= output / input

= P/E

=55000 / 215111.1

= 0.2557

= 25.6% to 1 decimal place.

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As a blacksmith heats a piece of iron, the iron glows red, then yellow, then white. The iron provides a demonstration of which p
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The answer is D. Blackbody radiation. The piece of iron glows red because its temperature is around 1000 K, then yellow because its temperature is around 2800 K, and then white because its temperature is around 5500K. This shows that the spectrum of the radiation is determined by absolute temperature, as when the temperature of a blackbody radiator increases, the peak of the radiation curve moves to shorter wavelengths. 
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2 years ago
5. A nail contains trillions of electrons. Given that electrons repel from each other, why do they not then fly out of the nail?
diamong [38]

Answer:

Nails are made of iron. Iron consists of 26 protons and 26 electrons. protons are positively charged and electrons are negatively charged, so this force of attraction keeps the electrons together.

If electrons repel from each other, the positively charge protons and nucleus allow them to move in a definite orbit and prevent them flying out of the nail.

4 0
2 years ago
A 1.25 in. by 3 in. rectangular steel bar is used as a diagonal tension member in a bridge truss. the diagonal member is 20 ft l
pentagon [3]

Answer:

axial stress in the diagonal bar =36,000 psi

Explanation:

Assuming we have to find axial stress

Given:

width of steel bar: 1.25 in.

height of the steel bar: 3 in

Length of the diagonal member = 20ft

modulus of elasticity E= 30,000,000 psi

strain in the diagonal member ε = 0.001200 in/in

Therefore, axial stress in the diagonal bar σ = E×ε

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5 0
2 years ago
Part A
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
Ann and Bob are carrying a 18.5 kg table that is 2.25 m long. A 8.33 kg box sits on the table 0.750 m from Ann. How much lift fo
IgorC [24]

Answer:

F = 118 N

Explanation:

Assume Ann and Bob lift at their respective ends of the table

Sum moments about Bob's position to zero.

Let F be Ann's upward force

F[2.25] - 18.5(9.80)[2.25 / 2] - 8.33(9.80)[0.750] = 0

F = 117.86133333...  

7 0
2 years ago
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