12. a boy of mass 50 kg running 5m/s jumps on to a 20kg trolley
travelling in the same direction at 1.5m/s. find their common
velocity. assume that there is no external unbalanced force
working in the horizontal direction.

Acube has a volume of 2011 cubic inches. what is the angle measure between a side of a cube and its interior diagonal?

Two thin 80.0- cm rods are oriented at right angles to each other. each rod has one end at the origin of the coordinates, and one of them extends along the x- axis while the other extends along the yaxis. the rod along the x- axis carries a charge of - 15.0 μ c distributed uniformly along its length, and the other rod carries 15.0 μ c uniformly over its length. find the magnitude and direction of the net electrical force that these two rods exert on an electron located at the point (40.0 cm, 40.0 cm). (e

Aperson walks first at a constant speed of 4.89 m/s along a straight line from point a to point b and then back along the line from b to a at a constant speed of 2.95 m/s. what is the average speed over the entire trip?