A plank AB 3.0m long weighs 20kg and with it's centre of gravity 2.0m from the end A. it rests on two supports at C and D. i) compute the values of the reaction forces R1 and R2 at C and D . ii) how far from D and in which side of it must a mass of 24kg be placed on the plane so as to make the reaction equal? what are their values ? iii) without this 24kg ,what vertical force applied at B will just lift the plank clear of D ? what is then the reaction at C

During spring semester at mit, residents of the parallel buildings of the east campus dorms battle one another with large catapults that are made with surgical hose mounted on a window frame. a balloon filled with dyed water is placed in a pouch attached to the hose, which is then stretched through the width of the room. assume that the stretching of the hose obeys hooke's law with a spring constant of 89.0 n/m. if the hose is stretched by 5.80 m and then released, how much work does the force from the hose do on the balloon in the pouch by the time the hose reaches its relaxed length? unitst 3 number-1497 the tolerance is +/-5% open show work click if you would like to show work for this question:

22. the effect of threshold braking is to a cause skids. b. lock wheels. c. prevent locking of wheels. d. increase stopping distance.

What is the measure of a change in an objects velocity?