A particle move in a straight line such that it's distance s metres from a fixed point 0 at time t is given by s=1.5t -10.5t -4t +10. If it's velocity after k seconds is 3.5m/s, find the value of k?

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex