Engineering » Page 121

Emerson Shelton

Engineering

Crawling in heavy smoke or extreme heat can increase

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Engineering

4.13 Compare thermoplastic and thermosetting polymers (a) on the basis of mechanical characteristics upon heating and (b) according to possible molecular structures.

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Engineering

The Phoenix with a mass of 390 kg was a spacecraft used for exploration of Mars. Determine the weight of the Phoenix, in N, (a) on the surface of Mars where the acceleration of gravity is 3.73 m/s2 and (b) on Earth where the acceleration of gravity is 9.81 m/s2.

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Engineering

If you put a straw into a glass of water, the straw looks bent, although nothing has really happened to the straw. The term that describes this property of light is

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Engineering

What can you do to protect your hands from any hazards on your worksite? Select the 2 answer options that apply. Use your gloves correctly Avoid jobs that could hurt your hands Always wear gloves Inspect your gloves for any damage before wearing

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Engineering

How many steps is a player allowed to take after catching a ball while running

a. 5 b. 2 c. 10 d. 1

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Engineering

While it seems rather than obvious that engineers need to consider the end user, how might this perspective get lost in the design process?

critical thinking question

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Engineering

If a motor driven by PWM using half-bridge operation has a speed of 1,426 rpm at a duty cycle of 100% (full forward), what will its speed be at a duty cycle of 47%

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Engineering

An 1,840 W toaster, a 1,420 W electric frying pan, and a 70 W lamp are plugged into the same outlet in a 15 A, 120 V circuit. (The three devices are in parallel when plugged into the same socket).

A) What current is drawn by each device?

B) Will this combination blow the 15-A fuse?

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Engineering

A permanent magnet DC motor has an armature resistance of 0.5 Ω and when a voltage of 120 V is applied to the motor it reaches a steady-state speed of rotation of 20rev/s and draws 40A. What will be:

(a) the power input to the motor?

(b) the power loss in the armature?

(c) the torque generated at that speed?

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Engineering

A cylindrical hot water storage tank (see sketch) for a set of collectors is located in the basement of a dwelling. The tank is made of 0.080" thick steel and insulated with 3" thick fiberglass batt insulation. If the basement air temperature is 65ºF and the liquid in storage tank is at 120ºF, what are the heat losses through the vertical cylindrical surface of the tank? Assume inner surface of tank is at 120ºF. Ignore any radiation heat losses

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Engineering

If an object moves 2 meters to the left in 1 second, what is the velocity of the object?

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Engineering

An alloy to be used for a spring application must have a modulus resilience of at least 0.72 * 106 J/m3 (0.72 * 106 Pa). What must be its minimum yield strength (in MPa) ? Assume that the modulus of elasticity for this alloy is 101 GPa.

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Engineering

At steady state, a refrigerator whose coefficient of performance is 3 removes energy by heat transfer from a freezer compartment at 0 degrees C at the rate of 6000 kJ/hr and discharges energy by heat transfer to the surroundings, which are at 20 degrees C. a) Determine the power input to the refrigerator and compare with the power input required by a reversible refrigeration cycle operating between reservoirs at these two temperatures. b) If electricity costs 8 cents per kW-hr, determine the actual and minimum theoretical operating costs, each in $/day

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Engineering

Which of the following was a difference between life in England and in the British North American colonies? A. The right to vote was more widespread in England than it was in the colonies. B. British colonists did not have an established church. C. There was greater social and economic equality in England than in the colonies. D. British colonists could not hold assemblies or meetings.

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