5.) A rock with a mass of 5-kg and moving at 20 m/s collides head on with a 10-kg rock. After the collision, both rocks come to rest. Determine the initial velocity of the 10-kg rock.
(Be careful with signs!!!)

As shown in fig. p3.64, a closed, rigid tank fitted with a fine-wire electric resistor is filled with refrigerant 22, initially at 2108c, a quality of 80%, and a volume of 0.01 m3. a 12-volt battery provides a 5-amp current to the resistor for 5 minutes. if the final temperature of the refrigerant is 408c, determine the heat transfer, in kj, from the refrigerant.

Many machines- including inclined planes such as ramps- increase the strength of the force put into the machine but decrease the distance over which the force is applied.

An engineer designs a roller coaster so that a car travels horizontally for 162 ft, then climbs 127 ft at an angle of 31.0° above the horizontal. it then moves 127 ft at an angle of 46.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)