Answer to Question #58098 in Physics for Christbeauty

Question

12 A 10-g bullet of unknown speed is shot horizontally into a 2-kg block of wood suspended from the ceiling by a cord. The bullet hits the block and becomes lodged in it. After the collision, the block and the bullet swing to a height 30cm above the original position. What was the speed of the bullet? (This device is called the ballistic pendulum). Take
g=9.8ms−2
700 m/s
640 m/s
354 m/s
487 m/s

13 A uniform plank AB 30 m long, weighing 100 N is pivoted at points P, Q which are 5 m from the ends A and B respectively. A boy of weight 250 N stands at a point D on the plank, 1 m away from Q and the arrangement is in equilibrium. Determine the reaction
R1
and
R2
at the supports.
77.5 N, 245.5 N
105.5 N 33.5 N
37.5 N, 312.5 N
27.5 N, 232.5 N