Jim and Mary Are Carrying Bob on a Horizontal Stretcher

Multiple Choice

Jim and Mary are carrying Bob on a horizontal stretcher.The uniform stretcher is 2.00 m long and weighs 80 N.Bob weighs 600 N.Bob's center of gravity is 80 cm from Mary.Jim and Mary are at the ends of the stretcher.The force that Mary is exerting to support the stretcher,with Bob on it,is

A) 550 N.
B) 400 N.
C) 300 N.
D) 280 N.
E) 200 N.