Vertical circle-direction of a force?

In summary: If the normal force is downward, the person will be pushed into their seat. In summary, the direction of the force on a car moving in a vertical circle depends on the magnitude of the normal force. When the normal force is less than the weight, the direction of force is upwards, and when it is more, the direction of force is downwards. This affects the direction of motion for the person inside the car, as an upward normal force will push them towards the roof of the car, while a downward normal force will push them into their seat.
  • #1
lu6cifer
16
0
Vertical circle--direction of a force?

Vertical circle--direction of a force?
An amusement park ride consists of a car moving in a vertical circle on the end of a rigid boom of negligible mass. The combined weight of the car and riders is 4.5 kN, and the circle's radius is 12 m.

(a) At the top of the circle, what are the magnitude Fb and direction (up or down) of the force on the car from the boom if the car's speed is v = 5.0 m/s?

(b) At the top of the circle, what are the magnitude Fb and direction (up or down) of the force on the car from the boom if the car's speed is v = 15 m/s?

I have the work and the answers, so I know how this works mathematically. For a, the normal force is positive, so the direction of force is up. But, for b, the normal force is negative, so the direction of force is down. However, since they're at the top for both scenarios, shouldn't there only be one direction of force anyway?

[Note: direction of motion is positive, W = weight, N = normal force]
For a:
W - N = mv2 / r
(v = 5 m/s)
N = 3.59kN

For b:
W - N = mv2 / r
(v = 15 m/s)
N = -4.11kN
 
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  • #2


When the car is moving in the vertical circle, centrifugal force acts on it which is away from the centre. When the weight is more than this force, the net force is in the down ward direction. Other wise it is upwards.
 
  • #3


rl.bhat said:
When the car is moving in the vertical circle, centrifugal force acts on it which is away from the centre. When the weight is more than this force, the net force is in the down ward direction. Other wise it is upwards.

So, when the centripetal force, ie, the mv2/r part of the equation is less than W, that means that the normal force is directed upwards, and if it's more than W, the normal force is directed downwards?

And, what would an upward normal force mean as opposed to a downward one if this situation were in real life?
 
  • #4


In the real life, a person sitting in the car will be thrown to the roof of the car if the normal force is upwards.
 

1. What is a vertical circle-direction of a force?

The vertical circle-direction of a force refers to the path that a force takes when it acts on an object moving in a vertical circle. It is the direction in which the force is applied, which can either be towards the center of the circle (centripetal force) or away from the center (centrifugal force).

2. How does the direction of a force affect an object's motion in a vertical circle?

The direction of a force in a vertical circle is crucial in determining the object's motion. If the force is directed towards the center, the object will continue to move in a circular path. If the force is directed away from the center, the object will move away from the circle and potentially break its circular motion.

3. What is the difference between centripetal and centrifugal forces?

Centripetal force is the force that acts towards the center of a circle, keeping an object moving in a circular path. Centrifugal force is the equal and opposite reaction to the centripetal force, acting away from the center of the circle. It is often referred to as a fictitious force, as it only appears in a non-inertial reference frame.

4. How does the vertical circle-direction of a force change as an object moves through the circle?

The vertical circle-direction of a force changes as the object moves through the circle. At the top of the circle, the direction of the force is downwards (towards the center) to maintain the object's circular motion. At the bottom of the circle, the direction of the force is upwards (away from the center) to counteract gravity and prevent the object from falling out of the circle.

5. What other factors can affect the direction of a force in a vertical circle?

Besides the direction of the force itself, other factors that can affect the direction of a force in a vertical circle include the mass of the object, the speed of the object, and the radius of the circle. These factors can impact the strength and direction of the force needed to maintain the object's circular motion.

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