中国石油大学工程力考试Exam(__2_mid).docVIP

中国石油大学（北京）2009--2010学年第2学期 《 Engineering Mechanics I》期中考试试卷/A Class: Name： Registration No.： Score： No. I II III IV V Total Score Date: May 4, 2010 For the each question following, please choose a right answer. (5*5=25 Points). (5 Points) A man is trying to move a packing crate across the rough floor by applying a horizontal force P. The weight of the crate is W. W=250N. If P=60N and (S=0.3, the crate will________. slip (2) tip not move (4) slip and tip 2. (5 Points) A homogeneous bar AB with weight P is hanged by a vertical cable CD. A and B contact with two smooth vertical walls respectively. The reaction at A is FA and at B FB. Then, (1) FA FB (2) FA FB (3) FA= FB 3. (5 Points) A compound pendulum is made of a homogeneous bar (mass m1) and homogeneous plate (mass m2). Point M (mass m3) relatively moves along the rim of the plate with uniform velocity u. At the position as shown, if the angular velocity of the pendulum is (，the angular momentum of the system about O is LO=______________. (1) (2) (3) 4. (5 points) Two homogeneous circular plates A and B with same weight and radius are placed in a smooth horizontal plane. The two plates start to move from rest undergoing two forces F and F’ respectively. If F = F’, the momentums of the two plates have the relation as _______. (1) PA =PB (2) PA PB (3) PA PB 5. (5 points) The crank OA of the steam engine is rotating uniformly about O at (=constant. OA=0.4m, AC=BC=0.2m. At the instant as shown that (=90(, the connecting rod ACB is_____, the linking member CD is_____ and the push rod DE of the steam valve is_____. (1) translating (2) rotating (3) at rest Fig. Prob. I-5 Fig. Prob. II II．(20 points) For the continuous beam with loads as shown, find the reactions at A, B and C. (15 points) The crank OA of the transmission mechanism of the mini-puncher is rotating a