Mechanical Engineering Review Online

1. An engine burns 2.4 liter of fuel each 12 minutes. The fuel has a specific gravity of 0.80, and a heating value of 42 MJ/kg. The engine has an efficiency of 33%. What is the brake horsepower of the engine?

a. 45 hp

b. 50 hp

c. 55 hp

d. 60 hp

2. What is the decrease in height of a 3.2 kg body whose kinetic energy increases from 28 J to 128 J as a result of moving downward along an inclined plane?

a. 3.19 m

b.4.20 m

c. 2.90 m

d. 5.28 m

3. An engine has an efficiency of 35%. It uses 6 gallons per hour. Gasoline has a heating value of 20300 Btu/lbm and specific gravity of 0.85. What is the power output of the engine?

a. 75.0 kW

b. 82.6 kW

c. 88.3 kW

d. 92.7 kW

4. A power 15 kW is supplied to the motor of a crane. The motor has an efficiency of 82%. With what constant speed does the crane lift a 1550 lbf weight?

a. 3.8 m/s

b. 4.2 m/s

c. 2.6 m/s

d. 1.8 m/s

5. A 5-lbm solid circular gear with a 3.8-in radius of gyration is turned by a motor running at 1400 rpm. What is the kinetic energy of the gear?

a. 167.3 ft-lb

b. 158.8 ft-lb

c. 161.2 ft-lb

d. 187.7 ft-lb

6. What is the kinetic energy of a 1200 lb motorcycle traveling at 70 mph?

a. 196405.9 ft-lb

b. 208111.3 ft-lb

c. 182771.0 ft-lb

d. 170077.8 ft-lb

7. Two particles collide, stick together, and continue their motion together. Each particle has a mass of 12 grams, and their respective velocities before collision were 18 m/s and 95 m/s. What is their common velocity after collision?

a. 50.3 m/s

b. 56.5 m/s

c. 68.7 m/s

d. 58.2 m/s

8. A car of mass m=1100 slugs accelerates in 15 seconds from rest at a constant rate to a speed of v=28 ft/s. What is the resultant force on the car due to this acceleration?

a. 1888.3 lbf

b. 2053.4 lbf

c. 2220.7 lbf

d. 1506.8 lbf

9. A 50 ton rail moving at 1.5 mph is instantaneously coupled to a stationary 80 ton rail car. What is the speed of the coupled cars?

a. 0.8813 mph

b. 0.6871 mph

c. 0.5770 mph

d. 0.4718 mph

10. The flow rate of water through a cast iron pipe is 4100 GPM. The pipe is 1.4 ft and the coefficient of friction f=0.0157. What is the pressure drop over a 260 ft length of pipe?

a. 99.5 psf

b. 84.6 psf

c. 82.2 psf

d. 90.3 psf

11. Three kilogram per second water enters the heater at 34 deg C and leaves at 95 deg C. Only 75% of the electrical energy is converted to heat energy. If the heater is connected to 2000 V source, find the current flowing through the heater.

a. 420.8 amp

b. 580.8 amp

c. 530.5 amp

d. 510.8 amp

12. A heater is rated 1200 watts. If the load resistance is 12 ohms, find the current flowing to the circuit.

a. 30 amp

b. 20 amp

c. 10 amp

d. 15 amp

13. A single phase AC circuit is connected to a 220 V source that draws 11 A current. If apparent power of the circuit is 2600 VA. Find the power factor of the circuit.

a. 85.2%

b. 88.8%

c. 76.1%

d. 93.1%

14. Two resistors 3 ohms and 12 ohms are connected in series and the combination is connected across the 450 V source. Find the voltage across the 3 ohms resistor.

a. 90V

b. 85V

c. 80V

d. 95V

15. An ideal transformer has 280 primary turns and 50 secondary turns. What is the secondary voltage if the primary voltage is 200 V?

a. 30.2V

b. 35.7V

c. 38.1V

d. 40.8V

16. The equivalent capacitance of capacitors C₁ and C₂ connected in series is 7.6 microfarad. If the capacitance C₁=9.8 microfarads, what is the capacitance C₂?

a. 30.2 μF

b. 33.9 μF

c. 38.4 μF

d. 42.8 μF

17. The voltage drop across a device is 230 V and the current drawn is 18 amps. What is the power rating of this device?

a. 3.5 hp

b. 4.5 hp

c. 5.5 hp

d. 6.5 hp

18. A charge of 630 coulombs passes through a wire every 18 seconds. What is the current in the wire?

a. 35 amps

b. 30 amps

c. 40 amps

d. 45 amps

19. If a car travels at 20 m/s and the track is banked at 9 deg, what is the smallest radius it can travel without skidding?

a. 200.0 m

b. 281.1 m

c. 234.5 m

d. 257.4 m

20. Traffic travels at 65 mph around a banked highway curve with a radius of 1800 ft. What banking angle is necessary such that friction will not be required to resist the centrifugal force?

a. 6.3 deg

b. 8.2 deg

c. 7.6 deg

d. 5.1 deg

21. A 28 inches long rod floats vertically in water. It has a 1.5 in2 cross section and has a specific gravity of 0.75. What length L is submerged?

a. 18 ft

b. 19 ft

c. 21 ft

d. 20 ft

22. A perfect venturi with throat diameter of 1.0 inches is placed horizontally in a pipe with 5 inches inside diameter. One hundred (100) lb of water flow through the pipe each second. What is the difference between the pipe and venture throat static pressure.

a. 432.7 psi

b. 457.2 psi

c. 580.0 psi

d. 591.2 psi

23. A cylindrical pipe with water flowing downward at 0.03 m³/s, having top diameter of 0.07 m, bottom diameter of 0.03 m and a height of 1.83 m. Find the pressure between the pipe.

a. 852.3 kPa

b. 901.1 kPa

c. 820.1 kPa

d. 880.1 kPa

24. Find the fraction of the volume of a solid object with specific gravity of 7.8 floats above the surface of a container of mercury?

a. 0.4265

b. 0.4626

c. 0.4879

d. 0.4779

25. A block of wood 0.5 m x 0.5 m x “y” meters in dimension was thrown in the water it floats with 0.16 m projecting above the water surface. The block was thrown into a container of liquid having a specific gravity of 0.92 and it floats with 0.13 m projecting above the liquid surface. Find the value of “y” and the specific gravity of the block, respectively.

a. 0.5049 m

b. 0.6481 m

c. 0.7681 m

d. 0.8817 m

Answer Key (Handwritten)