How to find the normal force given the center of gravity and the radius

In summary, to find the normal force on each hand and foot while doing a push-up, you must analyse the torques about the fulcrum, which is located at the center of gravity at the waist. This is a torque problem, so you must determine the type of lever being used. Assume there are no differences between the left and right hands and feet, and only consider the normal force at the top or bottom of the push-up while ignoring any angular acceleration.
  • #1
Pinkchika88
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Homework Statement


a person is doing pushups and its weight is 584 N, center of gravity is at waist and from waist to hands=.410m and from waist to feet=.840m. find the normal force on each hand and each foot


Homework Equations





The Attempt at a Solution


do u have to find the weight on top half of body and then weight on lower half (the force being applied by the hands/feet)?
 
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  • #2
Pinkchika88 said:

Homework Statement


a person is doing pushups and its weight is 584 N, center of gravity is at waist and from waist to hands=.410m and from waist to feet=.840m. find the normal force on each hand and each foot
This is a torque problem. Analyse the torques about the fulcrum. Where is the fulcrum? What kind of a lever is this? Find the normal force at the top (or bottom) of a push- up - ie. ignore any angular acceleration. Also, assume there are no differences between left and right hands and between left and right feet.

AM
 

1. What is the formula for calculating the normal force given the center of gravity and radius?

The formula for calculating the normal force is FN = m x g x cos(θ), where m is the mass of the object, g is the acceleration due to gravity, and θ is the angle between the vertical and the line connecting the center of gravity and the point of contact.

2. How do I determine the direction of the normal force?

The direction of the normal force is always perpendicular to the surface of contact. This means that it is always directed towards the center of the object or surface in contact.

3. Can the normal force be greater than the weight of the object?

Yes, the normal force can be greater than the weight of the object if the object is accelerating or if it is on an inclined plane. In these cases, the normal force is offsetting the component of the weight that is parallel to the surface.

4. How do I find the center of gravity of an object?

The center of gravity of an object can be found by balancing the object on a pivot point and marking the spot where it balances. This spot is the center of gravity. Alternatively, it can be calculated by taking the weighted average of the individual masses of the object.

5. What is the significance of calculating the normal force?

The normal force is important in understanding the forces acting on an object in contact with a surface. It can help determine the stability of an object and its ability to remain in equilibrium. Additionally, it is a crucial component in many physics equations and can be used to calculate other forces, such as friction and tension.

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