## Monday, July 5, 2010

### Mechanical Engineering Review Question: Mechanics (Computation)

Mathematics and Engineering Sciences coupled with Engineering Economy comprise 35% of the board exam rating. This is mandated by Republic Act 8495 or The Philippine Mechanical Engineering Act of 1998. With that in mind, I created practice questions for review in preparation for the upcoming 2nd Phase of Mechanical engineering Board Exam this October 2010. I have below some practice questions specifically on the topic, Engineering Mechanics. I hope it will help a bit specially to those who are self-reviewing.

1. A 20kg block is resting in a horizontal surface. Calculate the force required to move it if the coefficient of static and dynamic friction are 0.75 and 0.6 respectively.
a. 118 N
b. 147 N
c. 196 N
d. 132 N

2. A 100kg object is sliding over a surface with static and dynamic coefficient of friction values of 0.5 and 0.3 respectively. If the initial velocity of the object is 10m/s, how long will it travel before it completely stops?
a. 17 m
b. 10.2 m
c. 20.4 m
d. 34 m

3. A 1kg ball is tied at the end of a 1.5m long rope and then rotated at the speed of 100 RPM. Calculate the tension on the rope.
a. 263.2 N
b. 41 N
c. 16.7 N
d. 164.5 N

4. A bullet is fired vertically from a gun situated 2 m above the ground. If the initial speed of the bullet is 100m/s, how high will it travel before it starts falling? Assume negligible air resistance.
a. 509.7 m
b. 507.7 m
c. 501.7 m
d. 511.7 m

5. A missile is fired from North Korea and is targeted towards South Korea. If the distance between the two countries is 100km and the firing angle is 45 degrees, at what velocity should the missile be fired to reach its target? Assume negligible air resistance.
a. 1981m/s
b. 120 m/s
c. 991 m/s
d. 556 m/s

6. Calculate the polar moment of inertia of a 30 cm diameter circular board.
a. 25312.5 cm^3
b. 79521.6 cm^4
c. 12656 cm^3
d. 12656.5 cm^4

7. A 20mm thick, 50 cm in diameter wheel made of cast iron (density: 6.0kg/cu m) starts rotating from rest and in 1 minute, attained an angular speed of 200 RPM. Calculate the angular acceleration in rad/s2?

8. A 2kg ball starts rolling down from the top of a 100m-high hill towards the plains. Calculate the final speed of the ball when it reaches the foot of the hill. Assume negligible friction.
a. 31.3 m/s
b. 62.6 m/s
c. 14 m/s
d. 44.3 m/s

9. A 500kg car is moving around a 500 m radius road with 5 degrees banking. If the minimum friction between the tires and the road is 0.2 during rainy days, calculate the maximum speed limit.
a. 136 kph
b. 112 kph
c. 74 kph
d. 83 kph

10. A 2kg object with a velocity of 10m/s hits a 3kg object at rest, sticks with it and move together in the same direction. Find the resulting velocity.
a. 6 m/s
b. 5 m/s
c. 4m/s
d. 3m/s

Answers and solution will be posted after one week. Let me know if there's any concern with the question or the choices.