How Do You Calculate Forces on Inclined Planes?

  • Thread starter Thread starter jarny
  • Start date Start date
  • Tags Tags
    Forces
AI Thread Summary
The discussion focuses on calculating forces on inclined planes through two specific problems involving tension, normal force, and acceleration. For the first problem, the user calculates the tension in the cord and the normal force acting on an 8.2 kg block on a 37° incline, but struggles with the acceleration calculation after cutting the cord. In the second problem, a 104 kg crate is pushed up a frictionless ramp at a 29° angle, where the user correctly finds the horizontal force needed but encounters issues with calculating the normal force. Key points include the importance of resolving gravitational forces into components and applying Newton's second law. The conversation highlights the need for clarity in force calculations on inclined planes.
jarny
Messages
15
Reaction score
0

Homework Statement



I have two questions:

1. Let the mass of the block be 8.2 kg and the angle θ be 37°. Find (a) the tension in the cord and (b) the normal force acting on the block. (c) If the cord is cut, find the magnitude of the block's acceleration.

2.In the figure, a crate of mass m = 104 kg is pushed at a constant speed up a frictionless ramp (θ = 29°) by a horizontal force f-> . The positive direction of an x-axis is up the ramp, and the positive direction of a y-axis is perpendicular to the ramp. (a) What is the magnitude of f-> ? (b) What is the magnitude of the normal force on the crate?



Homework Equations



F_net=ma
Maybe T-m*g*sin(theta)=ma


The Attempt at a Solution



Ok, for 1.a. I used 8.2kg*9.8m/s^2*cos(29)=48.3619N to find the tension on the cord. For b I used 8.2*9.8*sin(29)=64.1783N. For 3. I am having trouble because my T and mgsintheta are the same.

For 2a. I used 104kg*9.8m/s^2tan(29) to get 564.92N and for B is got 1019N*cos(29) but the computer says this is wrong. The only one I got right was 2.a, 1.a and 1.b were revised so they might be right.



Can anyone help? Thank you very much
 
Physics news on Phys.org
Welcome to PF.

What is the diagram of the problems you are solving.
 
Last edited:
1)The force component of gravity pointing down the ramp is sinθ.

Hence the Tension to off set that in the direction up the ramp is m*g*sinθ = m*a where a is the answer to your part c.

The Cosθ component of g determines the force normal to the incline.

2) For part b you have two components of force to account for.

From the F you have F*sinθ
From mass and gravity you have m*g*Cosθ
 
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

Help with finding Normal Force of inclined plane
Replies
1
Views
3K
Finding the work done by a block
Replies
4
Views
3K
Tension force and acceleration Problem
Replies
1
Views
2K
Block on top of an inclined plane, with a rough surface, that moves with constant acceleration
Replies
41
Views
4K
Box and a Spring on on an inclined plane
Replies
11
Views
3K
How do you calculate the acceleration of a block sliding down a plane?
Replies
14
Views
2K
Friction force on an inclined plane
Replies
3
Views
2K
Using the sin function for a problem with a frictionless pulley and an incline
Replies
8
Views
1K
Rope between inclines with maximum length of hanging middle portion
Replies
46
Views
3K
Swinging Ball at Top of Circle: Forces & Energies
Replies
16
Views
2K

Hot Threads

Recent Insights

Back
Top