# Physics! plese help

A 1320-N uniform beam is attached to a vertical wall at one end and is supported by a cable at the other end. A 1960-N crate hangs from the far end of the beam. Using the data shown in the figure, find (a) the magnitude of the tension in the wire and the magnitudes of the (b) horizontal and (c) vertical components of the force that the wall exerts on the left end of the beam.

From the wall to the beam creates a 50 degree angle. From the beam to the crate is a 30 degree angle.

1. 👍
2. 👎
3. 👁
1. The drawing shows the beam and the five forces that act on it: the horizontal and vertical components S(x) and S(y) that the wall exerts on the left end of the beam, the weight W(b) of the beam, the force due to the weight Wc of the crate,
and the tension T in the cable. The beam is uniform, so its center of gravity is at the center of the beam, which is where its weight can be assumed to act. Since the beam is in equilibrium, the sum of the torques about any axis of rotation must be
zero ( Σ τ = 0) , and the sum of the forces in the horizontal and vertical directions
must be zero ( Σ F(x)= 0, Σ F(y)= 0) . These three conditions will allow us to determine the magnitudes of S(x), S(y), and T.
We will begin by taking the axis of rotation to be at the left end of the beam. Then
the torques produced by S(x) and S(y) are zero, since their lever arms are zero. When we set the sum of the torques equal to zero, the resulting equation will have only one unknown, T, in it. Setting the sum of the torques produced by the three forces equal to zero gives (with L equal to the length of the beam)
Σ τ = − W(b){0.5• L•cos30°} − W(c) •{Lcos30°} + T• {L•sin80°} = 0.
Algebraically eliminating L from this equation and solving for T gives
T = [W(b){0.5• L•cos30°} + W(c) •{Lcos30°}]/sin80º =
={1320• 0.5 •cos30°+1960• cos30°}/sin 80 º=2883 N.

Since the beam is in equilibrium, the sum of the forces in the vertical direction
must be zero:

Σ F(y) = + S(y) − W(b) − W(c) + T•sin50° =0
Solving for S(y) gives
S(y) =W(b)+W(c)-T•sin50 =1320+1960-2883•sin50°=1071 N.
The sum of the forces in the horizontal direction must also be zero:
Σ F(x)= + S(x) − T• cos50° = 0.
so that
S(x) = T• cos50° =2883•cos50° =1853 N.

1. 👍
2. 👎

## Similar Questions

1. ### Physics

A uniform 34.5-kg beam of length = 4.95 m is supported by a vertical rope located d = 1.20 m from its left end as in the figure below. The right end of the beam is supported by a vertical column. a) Find the tension in the rope.

2. ### Physics

A uniform rod 8m long weighing 5kg is supported horizontally by two vertical parallel strings at P and Q,and at distances of 2m,and 6m from one end. Weights of 1kg,1.5kg and 2kg are attached at distances of 1m, 5m and 7m

3. ### physics

a 10-m uniform beam of weight 100N is supported by two ropes at the ends. If a 400N erson sits at 2.0 m from the left end of the beam, what is the tension in the right rope?

4. ### Physics

A uniform beam of length 1.0 m and mass 16 kg is attached to a wall by a cable that makes an angle of 30 degrees with the end of the beam, as shown in the figure. The beam is free to pivot at the point where it attaches to the

1. ### physics

A 160kg horizontal beam is supported at each end. A 330kg piano rests a quarter of the way from one end. What is the vertical force on each of the supports?

2. ### physics

A uniform 8 m 1500 kg beam is hinged to a wall and supported by a thin cable attached 2 m from the free end of the beam as shown in the figure. The beam is supported at an angle of 30 degrees above the horizontal. a) free diagram

3. ### Physics

A 500N person stands 2.5m from a wall against which a horizontal beam is attached. The beam is 6m long and weighs 200N. A cable is attached to the free end of the beam and makes an angle of 45 to the horizontal and is attached to

4. ### Physics

A solid bar of length L = 1.32 m has a mass m1 = 0.751 kg. The bar is fastened by a pivot at one end to a wall which is at an angle θ = 35.0 ° with respect to the horizontal. (in other words, the angle between the wall and the

1. ### physics

The figure shows a uniform beam of mass m pivoted at its lower end, with a horizontal spring attached between its top end and a vertical wall. The beam makes an angle è with the horizontal. (a) Find expression for the distance d

2. ### physics

A uniform horizontal beam with a length of 8m and a weight of 200N is attached to a wall by a pin connection. Its far end is supported by a cable that makes an angle of 53° with the beam (Figure below). If a 600N person stands 2m

3. ### Physics

The figure (Figure 1) shows a model of a crane that may be mounted on a truck.A rigid uniform horizontal bar of mass m1 = 80.0 kg and length L = 5.30 m is supported by two vertical massless strings. String A is attached at a

4. ### Physics

A purple beam is hinged to a wall to hold up a blue sign. The beam has a mass of mb = 6.7 kg and the sign has a mass of ms = 17.4 kg. The length of the beam is L = 2.83 m. The sign is attached at the very end of the beam, but the