EEI Tech Mechanical Concept Flashcards

In a block and tackle with 4 supporting rope segments, how much effort is needed to lift a 400 lb load (ignoring friction)?

Answer: 100 lb

The load is shared by 4 rope segments: 400/4 = 100 lb of effort.

Two objects of equal mass fall in a vacuum, one heavier-looking than the other. Which hits the ground first?

Answer: They land at the same time

In a vacuum all objects accelerate at the same rate regardless of mass.

A wedge is best described as which combination?

Answer: Two inclined planes joined back to back

A wedge is two inclined planes joined to convert downward force into sideways splitting force.

If the diameter of a driving pulley is twice that of the driven pulley, the driven pulley will turn:

Answer: Twice as fast

A smaller driven pulley spins faster; half the diameter means double the speed.

What happens to the pressure exerted by a force when the area it acts on is reduced?

Answer: Pressure increases

Pressure equals force divided by area, so a smaller area means greater pressure.

A bimetallic strip bends when heated because:

Answer: The two metals expand at different rates

Different thermal expansion rates of the bonded metals cause the strip to curve.

Which statement about a balanced seesaw is correct?

Answer: The product of force and distance is equal on both sides

Balance occurs when force times distance (the moments) are equal on each side of the fulcrum.