Mechanical Concepts Flashcards

A technician needs to lift a heavy engine block. Using a pulley system with four rope segments supporting the load, how does the required effort change compared to lifting it directly?

Answer: The effort is reduced to one-fourth of the engine's weight.

The ideal mechanical advantage (IMA) of a pulley system is equal to the number of rope segments directly supporting the load. In this case, with four supporting ropes, the IMA is 4. This means the required effort to lift the engine is reduced to one-fourth of its actual weight.

Which of the following best describes the concept of torque?

Answer: A twisting force that causes rotation around an axis.

Torque is the rotational equivalent of linear force. It is a measure of how much a force acting on an object causes that object to rotate. It is calculated by multiplying the force by the perpendicular distance from the axis of rotation to the point where the force is applied.

A maintenance worker is using a 3-foot crowbar to lift a 150-pound object. The fulcrum is placed 0.5 feet from the object. What is the ideal mechanical advantage (IMA) of this lever setup?

Answer: 5

The Ideal Mechanical Advantage (IMA) of a lever is calculated by dividing the length of the effort arm by the length of the resistance (or load) arm. The effort arm is the distance from the fulcrum to the point where force is applied (3 ft - 0.5 ft = 2.5 ft). The resistance arm is the distance from the fulcrum to the load (0.5 ft). Therefore, IMA = 2.5 ft / 0.5 ft = 5.

Which type of gear is best suited for transmitting power between two non-intersecting, non-parallel shafts, often at a right angle?

Answer: Worm Gear

Worm gears are specifically designed to transmit power at a right angle between two shafts that do not intersect. They are also known for providing large gear reductions and high torque.

According to Newton's Third Law of Motion, when a rocket expels hot gases downwards, what is the 'reaction' force?

Answer: The force of the gases pushing the rocket upwards.

Newton's Third Law states that for every action, there is an equal and opposite reaction. The 'action' is the rocket pushing the hot gases downward. The 'reaction' is the hot gases pushing the rocket upward with an equal and opposite force, causing it to accelerate.

A technician observes two gears in a simple gear train. Gear A has 60 teeth and is driving Gear B, which has 20 teeth. If Gear A rotates one full revolution, how many revolutions will Gear B make?

Answer: Three revolutions

The gear ratio is calculated by dividing the number of teeth on the driven gear by the number of teeth on the driver gear (60 teeth / 20 teeth = 3). This means for every one revolution of the larger driver gear (Gear A), the smaller driven gear (Gear B) will complete three revolutions.