Shawn uses 45 N of force to stop the cart 27 meter from running his foot over. How much work does he do?

Which statement best describes resistance? resistance is a. how well a current will flow in a material and is measured in volts. b. how well a material conducts an electrical charge and is measured in ohms. c. the ability of a material to attract a positive charge to create a current. d. the ability of a material to repel neutral charges and is measured in ohms.

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

Protons and neutrons are found within the nucleus of an atom