The parallelogram linkage is used to transfer crates from platform A to platform B and i...

The parallelogram linkage is used to transfer crates from platform A to platform B and is hydraulically operated. The oil pressure in the cylinder is programmed to provide a smooth transition of motion where t is in seconds. Determine the force at D on the pin (a) just after the start of the motion with θ and t essentially zero and (b) when t = 1 s. The crate and platform have a combined mass of 200 kg with mass center at G. The mass of each link is small and may be neglected.