I need help can someone please help me its about geocentric and heliocentric

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.

Can somebody explain to me how newton's 3rd law relates to momentum? ~ap physics 1

The step-down transformer gives a current of 10a at 24v if the primary voltage is 240v calculate the 1_primary current 2_the power input 3_the power output