Why Do Reactions Differ in Problem P16.3 Compared to Standard Statics?

AI Thread Summary
In Problem P16.3, the reactions R_A and R_B are discussed in relation to their angles on an inclined plate. The original assumption is that the reactions should align with the incline's angle, but the book clarifies that R_A has both horizontal and vertical components due to friction and normal force. At point B, however, the surface is smooth, resulting in only a horizontal normal force with no vertical component. This distinction explains why the author presents the reactions as purely horizontal and vertical in the solution. Understanding these components is crucial for accurately analyzing the forces involved.
cipotilla
Messages
31
Reaction score
0
Hello, there something that doesn't make sense to me in the attached problem, P16.3. You can see from the diagram that you will have two reculting reactions, RA and RB. According to what I know from statics, the reactions will be at the same angle theta as the incline of the plate, see my solution on page 2. Why does the book's author, solve the problem using reactions that are purely horizontal and purely vertical?

Thanks.
 

Attachments

Physics news on Phys.org
cipotilla said:
According to what I know from statics, the reactions will be at the same angle theta as the incline of the plate, see my solution on page 2.
Why do you think that?
Why does the book's author, solve the problem using reactions that are purely horizontal and purely vertical?
He doesn't. At the A end of the plate, the reaction force of the surface on the plate has both horizontal (friction, F) and vertical (normal force, N_A) components. The author identifies the horizontal component as friction, but it's still part of the overall force that the surface exerts on the plate.

At the B end, the surface is smooth so there is no vertical component of reaction force, only the horizontal normal force (N_B).
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Splitting reaction into horizontal and vertical components
Replies
6
Views
2K
Moments Question (ENGAA 2019) -- Cable and Winch Lifting a Drawbridge
Replies
17
Views
3K
Reaction forces in a Static system
Replies
8
Views
3K
Calculating Theoretical Reaction Force of Ball Traveling in Semi-Circle
Replies
43
Views
4K
Rolling without slipping problem
Replies
42
Views
3K
Rope between inclines with maximum length of hanging middle portion
Replies
46
Views
3K
I Statics: When the reactions depend on the displacements
Replies
35
Views
4K
How Do You Correctly Cancel Angular Momentum in Physics Problems?
Replies
3
Views
1K
Angular Momentum- Conserved or not?
Replies
17
Views
408
Book plots position & force on the same graph, still gets right answer
Replies
8
Views
853

Hot Threads

Recent Insights

Back
Top