A pulley system lifts a 500-lb. block 2.0 feet with an effort of only 50 lb. If the 50 lb. moves 30 feet, calculate the efficiency of the pulley system.

In any ecosystem, the size of a population A. may change over time. B. only depends on the population's reproductive rate. C. always stays the same. D. only depends on the amount of resources available.

Describe Thomson's concept of the atom?

If an atom has seven electrons how many are in the second shell? A. 2 B. 5 C. 7 D. You need to know the number of protons to figure this out.

How much power does it take to do 450J of work in 5 sec

Carbon nonoxide formula

Along with an alpha particle what other product is produced in the alpha decay of americium-241

What does Newton's second law of motion say

Two sinusoidal waves are moving through a medium in the positive x-direction, both having amplitudes of 7.00 cm, a wave number of k=3.00m-1, an angular frequency of ω=2.50s-1, and a period of 6.00 s, but one has a phase shift of an angle ϕ=π12rad.

Which season does the Southern Hemisphere experience when it is tilted toward the sun? A. winter B. summer C. spring D. autumn

For an ideal fluid flowing through a horizontal pipe, Bernoulli's principle and the continuity equation state that the pressure within the pipe does which of the following? (Assume measurements are taken along the pipe in the direction of fluid flow.