There are free body diagrams in the picture, number (#). which of the diagram(s) shows an object with a net force down?

a.3 and 4

b.2 and 4

c.4 only

d.3 only

The position of a crate sliding down a ramp is given by x=(0.05t^3) m, y=(1.7t^2) m, z=(6−0.85t^5/2) m, where t is in seconds. (a) determine the magnitude of the crate's velocity when t = 2 s. (b) determine the magnitude of the crate's acceleration when t = 2 s.