A book is resting on a table. The table is raised on one end to an angle of 15° to the floor. If the book remains at rest, what keeps the book from sliding? A. rolling friction
B. static friction
C. sliding friction
D. fluid friction

Static Friction

Explanation: As you tilt the book you know that it will stay fixed to start with, but eventually, once the angle is large enough, the book will start to slide. It is the static friction force that holds the book in place at small angles of tilt.

i need the answer to this too but idk it ; -;

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s