أسئلة تدريب الهندسة الميكانيكية (اختبار جاهزية)

المجال 01 · الميكانيكا والاهتزازات

A beam fixed at both ends with a central load W in the middle will have zero bending moment at

1. Aone place
2. two places
3. Cno where
4. Dthree places

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.

المجال 02 · ميكانيكا المواد

A composite bar consists of a steel core and an aluminum sleeve bonded together, both of the same length, loaded axially in tension by a total force P. The cross-sectional areas are A_steel and A_aluminum, and the moduli are E_steel and E_aluminum. The bond ensures both materials undergo the same elongation. Which expression gives the fraction of the total load carried by the steel core?

1. (A_steel E_steel) / (A_steel E_steel + A_aluminum E_aluminum)
2. B(A_steel E_aluminum) / (A_steel E_aluminum + A_aluminum E_steel)
3. CA_steel / (A_steel + A_aluminum)
4. DE_steel / (E_steel + E_aluminum)

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.

المجال 03 · المواد والتصنيع

Hard steels and non-ferrous metal do not exhibit a definite yield point when pulled in the testing machine and for such cases a better measure of their elastic properties is defined by

1. AYield point stress
2. BYield point strain
3. Proof stress
4. DUltimate stress

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.

المجال 04 · ميكانيكا الموائع

Water flows through a horizontal pipe with a sudden contraction. The pressure drop across the contraction is measured to be 15 kPa. Assuming the flow is steady, incompressible, and frictionless, and neglecting changes in kinetic energy, what is the head loss due to the contraction? (Take density of water = 1000 kg/m³, g = 9.81 m/s²)

1. 1.53 m
2. B15.3 m
3. C0.153 m
4. D1.53 kPa

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.

المجال 05 · الديناميكا الحرارية

The same volume of all gases at same temperatureand pressure would represent their

1. Aspecific gravity
2. Bdensities
3. Cspecific weights
4. molecular weights

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.

المجال 06 · انتقال الحرارة

In a chemical plant, a hot process stream at 90°C is used to preheat a cold stream from 25°C to 65°C in a counter-flow heat exchanger. An engineer remarks that the heat duty of this exchanger is simply the product of the cold stream's mass flow rate, its specific heat, and the cold stream's temperature rise. Why is this statement valid for the cold stream?

1. Because the energy gained by the cold stream equals the product of its mass flow rate, specific heat, and temperature increase, which follows from an energy balance on that stream.
2. BBecause the heat duty of a heat exchanger is always determined by the hot stream alone, and the cold stream merely receives that heat without its own energy balance.
3. CBecause the specific heat of the cold stream is constant and therefore the temperature rise alone determines the heat duty regardless of flow rate.
4. DBecause the heat duty is the product of the overall heat-transfer coefficient, the heat-transfer area, and the temperature difference, which is equivalent to the cold stream's enthalpy change.

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.

المجال 07 · القياس والتحكم

A thermocouple with a Seebeck coefficient of 40 µV per °C is connected to an amplifier with a gain of 500. The amplifier output is read by a 12-bit ADC with a full-scale range of 0 to 5 V. The thermocouple reference junction is at 0 °C. If the amplifier output saturates at 5 V, what is the highest temperature that can be measured without saturation, and what is the temperature resolution of the system?

1. AHighest temperature 250 °C, resolution 0.005 °C.
2. BHighest temperature 250 °C, resolution 0.0024 °C.
3. Highest temperature 250 °C, resolution 0.061 °C.
4. DHighest temperature 125 °C, resolution 0.061 °C.

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.

المجال 08 · التصميم الميكانيكي

Find parametric equation for X-coordinates of hermite cubic spline curve having end points P0[4,4]; P1[8,5]

1. -5u3+8u2+u+1
2. B5u3+8u2+u+1
3. C8u3-5u2-u+1
4. D8u3+5u2+u+1

نموذج — المجموعة الكاملة، مع المراجعة المتباعدة والاختبارات، في التطبيق.