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Mechanical Comprehension

A fixed pulley is useful for which of the following?

changing the direction of the input force

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.

Math Knowledge

What is 9a - 7a?

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

9a - 7a = 2a

Mechanical Comprehension

A block and tackle with four pulleys would have a mechanical advantage of:

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.

Electronics Information

Current is the rate of flow of electrons per unit time and is measured in:

amperes

Current is the rate of flow of electrons per unit time and is measured in amperes (A). A coulomb (C) is the quantity of electricity conveyed in one second by a current of one ampere.

General Science

Reproductive haploids are also known as:

gametes

Reproductive (haploid) cells known as gametes have half as many (23) pairs of chromosomes as normal (diploid) cells. When the male gamete (sperm) combines with the female gamete (ovum) through meiosis to form a zygote, each gamete supplies half the chromosomes needed to form the normal diploid cells.

General Science

Which of the following describes the Earth's mantle?

all of these

Mantle makes up 84% of the Earth's volume and has an average thickness of approximately 1,800 miles (2,900 km). It is dense, hot, and primarily solid although in places it behaves more like a viscous fluid as the plates of the upper mantle and crust gradually "float" along its circumference.

Mechanical Comprehension

A = 5 ft., the green box weighs 50 lbs., and the blue box weighs 80 lbs. What does distance B need to be for this lever to balance?

3.13 ft.

In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B

For this problem, the equation becomes:

50 lbs. x 5 ft. = 80 lbs. x d_B

d_B = \( \frac{50 \times 5 ft⋅lb}{80 lbs.} \) = \( \frac{250 ft⋅lb}{80 lbs.} \) = 3.13 ft.

General Science

A subatomic particle found in the nucleus of an atom. It carries a positive electric charge. This desribes which of the following?

proton

A proton is a subatomic particle found in the nucleus of an atom. It carries a positive electric charge.

General Science

Which of the following members of the food chain are most alike?

scavengers and decomposers

Like decomposers, scavengers also break down the dead bodies of plants and animals into simple nutrients. The difference is that scavengers operate on much larger refuse and dead animals (carrion). Decomposers then consume the much smaller particles left over by the scavengers.

Arithmetic Reasoning

The __________ is the smallest positive integer that is a multiple of two or more integers.

least common multiple

The least common multiple (LCM) is the smallest positive integer that is a multiple of two or more integers.