Why Is the Resultant Force on the Blade Directed Downwards?

In summary, the conversation discusses the direction of the resultant force on a blade and why it is directed downwards towards A. It is explained that the horizontal component of the force acts 2.12kN to the left and 0.735kN upwards, resulting in a slanted upwards force. However, it is clarified that there is a typo in the equation and the resultant force is actually directed downwards towards A. It is also mentioned that the forces on the stream of water and on the blade are equal and opposite, in accordance with the principle of action and reaction.
  • #1
werson tan
183
1

Homework Statement


why the resultant force on blade is acted downwards (toward A)? why shouldn't it be slanted upwards ?
since the horizontal component of the force acted 2.12kN to the left , and 0.735kN upwards , we would get the resultant force acting slanted upwards , right ?

Homework Equations

The Attempt at a Solution

 

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  • #2
There is a typo in the Fx equation. The second 12cos60-12 should be 12cos60+12.
In the final answer, take note of the direction of the arrow. The angle is 19.11 degrees to the centreline (x axis). The "towards A" just means it is clockwise from that centreline.
 
  • #3
haruspex said:
There is a typo in the Fx equation. The second 12cos60-12 should be 12cos60+12.
In the final answer, take note of the direction of the arrow. The angle is 19.11 degrees to the centreline (x axis). The "towards A" just means it is clockwise from that centreline.
the horizontal component of force should be -1.272 N + 2.54 = 1.27N N to the right, whereas the direction and magnitude of vertical force is the same ? then , the direction of resultant of force should be upwards just like the diagram below?
 

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  • #4
werson tan said:
the horizontal component of force should be -1.272 N + 2.54 = 1.27N N to the right, whereas the direction and magnitude of vertical force is the same ? then , the direction of resultant of force should be upwards just like the diagram below?
The calculated Fx and Fy are forces on the stream of water. To get the forces on the blade you have to negate both, giving 2.12kN to the right and 0.735kN down.
 
  • #5
haruspex said:
The calculated Fx and Fy are forces on the stream of water. To get the forces on the blade you have to negate both, giving 2.12kN to the right and 0.735kN down.
isnt that the the resultant force on blade and forecs of steam of water are of same magnitude and same direction
?
 
  • #6
werson tan said:
isnt that the the resultant force on blade and forecs of steam of water are of same magnitude and same direction
?
Action and reaction are equal and opposite. The force the blade exerts on the stream of water is equal and opposite to the force the water exerts on the blade.
 
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Related to Why Is the Resultant Force on the Blade Directed Downwards?

What is the direction of resultant force?

The direction of resultant force is the direction in which all the individual forces acting on an object combine to create a single, net force.

How is the direction of resultant force determined?

The direction of resultant force is determined by vector addition, where each individual force is represented by an arrow and the arrows are drawn head-to-tail to determine the direction of the resultant force.

Can the direction of resultant force change?

Yes, the direction of resultant force can change if the individual forces acting on an object change in magnitude or direction.

What happens when the individual forces acting on an object are in opposite directions?

When the individual forces are in opposite directions, the resultant force will be in the direction of the larger force, and the magnitude of the resultant force will be the difference between the two forces.

How does the direction of resultant force affect the motion of an object?

The direction of resultant force determines the direction in which an object will accelerate. If the resultant force is in the same direction as the object's motion, it will increase its speed. If the resultant force is in the opposite direction, it will slow down the object's motion.

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