Dallas says that any change in velocity is directly proportional tothe time interval over which the change took place. Dana says thatis true only when the acceleration is constant. Which one, ifeither, is correct?
a. Dana, because it is true then the acceleration is constant
b. Dallas, because we can define ax, avg so thatDvx= ax, avgt.
c. Dallas, because ax, avg always is equalto
d. Allthe above are correct.
e. Only(a) and (b) above are correct

Three different objects, all with different masses, are initially at rest at the bottom of a set of steps. each step is of uniform height . the mass of each object is a multiple of the base mass : object 1 has mass 4..00m , object 2 has mass 1..96m , and object 3 has mass . when the objects are at the bottom of the steps, define the total gravitational potential energy of the three-object system to be zero. if the objects are then relocated as shown, what is the new total potential energy of the system? each answer requires the numerical coefficient to an algebraic expression. each algebraic expression is given using some combination of the variables , , and , where is the acceleration due to gravity. enter only the numerical coefficient. (example: if the answer is 1..23mgd , just enter 1.23)

A2k pendulum has a speed of 1 m/s at a height of 1/2 meter

This energy transformation diagram represents the energy of a skateboarder moving along a half-pipe. as she skates toward the top of the half-pipe, her original kinetic energy is converted to potential energy and friction. how much of the energy is potential?