Using the mks units (meters-kilograms-seconds), suppose you have a spring with spring constant 4 n/m. you want to use it to weigh items. assume no friction. you place the mass on the spring and put it in motion. a) you count and find that the frequency is 0.8 hz (cycles per second). what is the mass? b) find a formula for the mass m given the frequency ω in hz

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.