A sled and rider have a total mass M. They are at rest on a snowy hill. The coefficient of static friction between the sled and the snow is s. Find an expression for the maximum angle of the hill's slope measured upward from the horizontal in terms of s. (Use the following as necessary: s and M.)

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)

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.

Which best describes the first law of thermodynamics as compared to the second law of thermodynamics? a. the first law describes how thermal energy is conserved but not the direction it moves. b. the first law describes the direction thermal energy moves but not how it is conserved. c. the first law describes how thermal energy can be created but not how it can be destroyed. d. the first law describes how thermal energy can be destroyed but not how it can be created.