Under which of these conditions will no image be formed (real or virtual) for an object placed in front of a concave mirror? A. The object is placed at the focal point on the principal axis. B. The object is placed at the center of curvature on the principal axis. C. The object is placed between the center of curvature and focal point on the principal axis. D. The object is placed between the focal point and the vertex on the principal axis.
ANSWER IS (A) FOR PLATO USERS

Moon effect. some people believe that the moon controls their activities. if the moon moves from being directly on the opposite side of earth from you to being directly overhead, by what percentage does (a) the moon's gravitational pull on you increase and (b) your weight (as measured on a scale) decrease? assume that the earth–moon (center-to-center) distance is 3.82 × 10^8 m, earth's radius is 6.37 × 10^6 m, moon's mass is 7.36 × 10^22 kg, and earth's mass is 5.98 × 10^24 kg.

Students design a model roller-coaster track. they place a rubber ball at the highest point on the track and let it go. the ball rolls along the track pulled only by the force of gravity. eventually, it comes to a stop. which change to the design will result in the ball moving the greatest distance?

How many atoms of nitrogen are in the chemical formula ni(w on