Which direction will the support force by the wall point when the force diagram is drawn? The book is held motionless against a wall by yout hand. (Up, down, legt or right?)
1.You apply a force F on the book in horizontal direction towards the wall.
2. The normal reaction of the wall on the book will be (say) N. For equilibrium in horizontal direction =>
F = N
3. The weight of the book M*g will act on the book in downward direction.
4. The frictional force Fr= mu*N will act on the book in vertically upward direction.
For equilibrium in vertical direction =>
mu*N = M*g
(the static mu will adjust itself to satisfy the above expression)
You can draw the force diagram showing the four forces acting on the book. So, the wall provides two forces for support - the normal reaction N and the frictional force Fr.
right
To determine the direction of the support force exerted by the wall when the book is held motionless against it, we need to consider Newton's third law of motion, which states that every action has an equal and opposite reaction.
In this case, your hand is exerting an upward force on the book to balance its weight and keep it motionless against the wall. According to Newton's third law, the book exerts an equal and opposite force downward on your hand.
Since the book is held motionless against the wall, the reaction force from your hand is transmitted through the book and ultimately exerted on the wall. Consequently, the support force exerted by the wall on the book will point in the opposite direction to the force you exerted with your hand. Therefore, the support force by the wall will point downward.