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Mechanical Comprehension

If the green box weighs 55 lbs. and is 3 ft. from the fulcrum, how far from the fulcrum would a 70 lbs. weight need to be placed to balance the lever?

2.36 ft.

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

Solving for d_b, our missing value, and plugging in our variables yields:

d_b = \( \frac{R_ad_a}{R_b} \) = \( \frac{55 lbs. \times 3 ft.}{70 lbs.} \) = \( \frac{165 ft⋅lb}{70 lbs.} \) = 2.36 ft.

Word Knowledge

Even though I forgot his birthday, I hoe my father accepts my belated card.

tardy

Past the normal or proper time.

Mechanical Comprehension

The mechanical advantage of a block and tackle is equal to which of the following?

the number of pulleys

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.

Word Knowledge

Kim, an eloquent speaker, was the best choice to make the presentation for the group.

articulate

Fluent, expressive.

Electronics Information

Use Ohm's Law to calculate the value of resistance in this circuit if voltage is 40 volts and current is 2 amps.

20 Ω

Ohm's law specifies the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = IR.

Solved for resistance, R = \( \frac{V}{I} \) = \( \frac{40}{2} \) = 20 Ω

Electronics Information

Which of the following is not an advantage of semiconductors over conductors?

a semiconductor conducts current better than a conductor

A semiconductor is a material that has a limited ability to conduct electrical current with conductivity between that of an insulator and that of a conductor. Silicon, a cheap and abundant material, is the most used semiconductor material although other materials are used in the electronics components made from semiconductors. The primary advantages of a semiconductor over a conductor is that the conductivity of a semiconductor can be varied under an external electrical field giving engineers precise control over complex circuits and, unlike conductors like metals, a semiconductor's conductivity increases with increased temperatures.

General Science

Changes to an object's speed or direction of motion are caused by which of the following?

a force

Force is applied to change an object's speed or direction of motion.

General Science

"An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force." This describes which of Newton's laws of motion?

first

Also known as the law of inertia, Newton's first law of motion states that An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Electronics Information

A transistor to an electronic circuit is like a _______________ to a house?

gate

A transistor works by allowing a small amount of current applied at the base to control general current flow from collector to emitter through the transistor. A transistor acts as a gate or switch for electronic signals.

Automotive Information

The air-fuel mixture is delivered to the combustion chamber by a(n):

intake valve

The combustion chamber is located in the cylinder head and contains the combustion of the air-fuel mixture. This mixture is delivered by an intake valve and the waste gases from combustion are removed from the combustion chamber by the exhaust valve.