Knowing that the board is 4 meters long, one child weighs 300 n and the other 250 n, where should one of the children sit so that the board remains horizontal? (lever)

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

Why can blue light and yellow light combine to produce white light? question 17 options: they are both primary colors of light. they absorb each other's wavelengths. because blue, yellow, and white are primary colors. they are complementary colors of light.

Which of the following is the phase that results when the moon is on the opposite side of the earth from the sun? a. quarter moon b. crescent moon c. new moon d. full moon